THE HONG KONG POLYTECHNIC UNIVERSITY
INSTITUE OF TEXTILES AND CLOTHING
MATERNITY GARMENT TREATMENT FOR THE RELIEF OF LOW BACK PAIN
SIMONE HO SIN MAN
A thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy
May 2008
DEDICATION
This thesis is dedicated to my family
Background Low back pain (LBP) is the most common musculoskeletal problem during pregnancy. Pregnant women traditionally wear maternity support belts for back discomfort and have experienced pain relief. However, the designs of these maternity support garments lack scientific research and their clinical efficacy remains elusive. Limited evidence is available to substantiate its putative beneficial effects. Aims This study aims to investigate the garment needs of pregnant women in terms of physical and psychological comfort, based on which to establish design criteria, to develop a maternity support garment, and to evaluate the effect in the maternity garment treatment for the relief of LBP. Methods This study was conducted in three phases: a) an exploratory phase, b) a developmental phase, and c) an evaluative phase. In the exploratory phase, a longitudinal study of 29 pregnant women was undertaken to investigate which biomechanical measures should be used to specify the functional requirements of the maternity support garment. In-depth interviews and wear trials were completed to elicit responses of pregnant women (10 in personal interviews and 14 in wear trials) on 8 maternity support garments. Fabric objective measurements of the same 8 tested garments and 16 alternative samples were conducted before material selection for the first garment prototype. In the developmental phase, the functional garment design criteria were determined and several prototypes were made based on DeJonge’s design framework. In the evaluative phase, the garment prototype was assessed in a pilot clinical study on 9 patients with LBP between gestational weeks 29-36. Pain intensity, functional status, biomechanical measures, and pregnancy outcomes were also investigated. Results The interviews generated five main themes of garment needs including supportive function, comfort, ease to put on and take off, aesthetics and safety. The wear trials showed that the most preferred garment consisted of a thin cotton fabric with soft and smooth handfeel which was invisible in fitting, allowed easy movements and convenience for toileting. The material tests identified the characteristics of the most favorable sample. The longitudinal study found that the centre of pressure and sagittal lumbar curvature can be used to determine the biomechanical effect. Based on these findings, four garment prototypes were developed to
i satisfy the design criteria developed under five main themes. The pilot clinical study suggested that the maternity support vest is feasible and comfortable to wear as an adjunct therapy to exercises and has promising effects on pregnancy-related low back pain. Conclusions The research deliverables not only improve the garment treatment for LBP in pregnant women, but also provide a new scientific basis for therapeutic garment design. The methodologies and the results in the interviews, wear trials, biomechanical study, prototyping and clinical trials contribute to future research on the effect of garment therapy.
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LIST OF PUBLICATIONS AND AWARDS
Major parts of the material presented in this thesis have formed the basis for papers that have been presented and published as follows:
Referred Journal Articles
1. Ho, S.S., Yu, W., Lao, T.T., Chow, D.H.K., Chung, J.W. & Li, Y. Comfort evaluation of maternity support garments in a wear trial. Ergonomics. 51(9): 1376-93. (2008). 2. Ho, S., Yu, W., Lao, T.T., Chow, D., Chung, J. & Li, Y. Effectiveness of maternity support belts in reducing low back pain during pregnancy: A review. Journal of Clinical Nursing. (2nd revision submitted in August 2008). 3. Ho, S., Yu, W., Lao, T.T., Chow, D., Chung, J. & Li, Y. Garment needs of pregnant women based on content analysis of in-depth interviews. Journal of Clinical Nursing. (1st revision submitted in July 2008). 4. Ho, S., Chow, D., Yu, W., Lao, T.T. & Chung, J. Relationship among biomechanical parameters during pregnancy. BMC Musculoskeletal Disorders. (1st revision in progress). 5. Ho, S., Yu, W., Lao, T.T., Chow, D., Chung, J. & Li, Y. Garment design for the relief of low back pain during pregnancy. Nursing Research (to be submitted in October 2008). 6. Ho, S., Yu, W., Lao, T.T., Chow, D., Chung, J. & Li, Y. Maternity support vest as an adjunct therapy for the relief of pregnancy-related low back pain: A pilot study. Journal of Clinical Nursing (to be submitted in October 2008).
Book Chapter
7. Ho, S., Luo, Y., Yu, W., & Chung, J. Physical and Physiological Health Effects of Intimate Apparel. In Yu W., Fan J.T., Harlock S.C. & Ng S.P, Innovation and Technology of Women's Intimate Apparel. Cambridge: Woodhead Publishing Limited, p.132-150. (2006).
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Conference Presentations and Publications
8. Ho, S., Yu, W., Lao, T., Chow, D., Chung, J. & Li, Y. (2007). Maternity support garment for the relief of low back pain. Oral presentation and abstract in the Proceedings of The 4th International Conference and Exhibition on Healthcare and Medical Textiles, Bolton, UK, 16 -18 July 2007, p. 26. 9. Ho, S., Yu, W., Lao, T., Chow, D., Chung, J. & Li, Y. (2007). Physical and psychological comfort evaluation of maternity support garments. Oral presentation and abstract in the Proceedings of the 9th Asian Textile Conference, Taiwan, R.O.C., June 28-30, p. O-51. 10. Ho, S., Yu, W., Lao, T., Chow, D., Chung, J. & Li, Y. (2007). The centre of pressure changes during pregnancy: An objective measure to evaluate the action of maternity support garment? Oral presentation and abstract in the Proceedings of The Sigma Theta Tau International Conference on Evidence-Based Practice in Nursing: Paradigms & Dialogue, Hong Kong, April 19-21, p.35. 11. Ho, S., Yu, W., Lao, T., Chow, D., Chung, J. & Li, Y. (2006) Maternity support garments for low back pain: A review. Poster presented and abstract in the Proceedings of International Fiber Societies Conference, Seoul, 30 May – 2 June, p.609-610.
Honours and Awards
1. Sir Edward Youde Memorial (SEYM) Fellowship, Sir Edward Youde Memorial Fund Council, 14 April 2007. 2. Mrs. Cheung Chan You Fong Grace Scholarship, The Hong Kong Polytechnic University, 31 March 2006. 3. Leung Chan Mo Ching Postgraduate Scholarship, Hong Kong Association of University Women (HKAUW), 10 December, 2005.
iv ACKNOWLEDGMENTS
I would like to acknowledge the special contributions of many individuals who gave of their time and wisdom to make this thesis a reality. First of all, I would like to sincerely thank my chief supervisor Dr. Winnie Yu, from the Institute of Textiles and Clothing, for her continuous guidance, advice and encouragement throughout the course of my PhD study. I have benefited deeply from her detailed and constructive feedback in guiding the article publication and thesis writing. I am especially grateful to my co-supervisors, Prof. Daniel Chow, from the Department of Health Technology and Informatics, for his expertise in the spine biomechanics, and his serious- mindedness and critical thinking in research has influenced the rigor of my research work; Prof. Joanne Chung, from the School of Nursing, for her expert advice on pain and the research design. My gratitude also extends to Prof. Terence Lao, from the Department of Obstetrics and Gynecology, the University of Hong Kong, for his valuable advice and criticisms on my research writing and career, and Prof. Li Yi, from the Institute of Textiles and Clothing, for his helpful comments. Special thanks for the pregnant subjects who participated in my research and the staff members of the Queen Mary Hospital for their friendliness and help, and in particular the arrangement of a private room, which facilitated the smooth flow of my data collection. I would like to thank the colleagues at the Hong Kong Polytechnic University, Mr. So, Joanne, Zerence, Sammy and Eddie for their technical support and assistance. A big thank you goes to Prof. Tao, Head of Textile Technology, the donors of the Postgraduate Scholarships, my parents and my sister Cynthia for their generosity and financial support. Most importantly, hearty thanks to my family (Kenneth and Polly, Cynthia and Michael, Kelvin and Karen, Jackie and Steffi, Louise, Isabel, William, Anna, Rachel, and Katie) for their love, support and understanding, and also to my friends especially to Ruby for her tireless support; Kitty, Justina and Ying for their supportive prayers. Above all, I cannot find meaning in all of this without my God, who has been a great source of strength and endurance all through this work, especially during many ‘sleepless nights’.
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TABLE OF CONTENTS Page Abstract i List of Publications and Awards iii Acknowledgements v Table of Contents vii List of Figures xiv List of Tables xvii List of Appendices xix Abbreviations xx
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CONTENTS
CHAPTER 1 INTRODUCTION Page
1.1 Background 1 1.1.1 Prevalence and significance of low back pain (LBP) 1 1.1.2 Maternity support belt for relieving LBP during 2 pregnancy 1.1.3 Existing maternity support garments 3 1.2 Statement of the problems 4 1.3 Objectives of this study 5 1.4 Research Methods 6 1.5 Significance of the study 7 1.6 Assumption 7 1.7 Delimitations 8 1.8 Organization of thesis 8
CHAPTER 2 LITERATURE REVIEW
2.1 Introduction 10 2.2 Terms and definitions of LBP 10 2.3 Definition of pain 12 2.4 Gate Control Theory (GCT) 13 2.5 Relevant anatomy of the lumbar spine and pelvis 15
2.5.1 Natural spinal curves 17 2.5.2 Sacroiliac joint 17 2.5.3 Vertebra 17 2.5.4 Global spinal muscles 17 2.5.5 Local spinal muscles 21 2.5.6 Spinal ligaments 22 2.6 Clinical presentation of PLBP and PPP 23 2.6.1 Pregnancy-related low back pain (PLBP) 23
vii 2.6.2 Pregnancy-related pelvic girdle pain (PPP) 23 2.6.3 Prevalence, onset, pain intensity and impact of PLBP and 24 PPP 2.7 Possible causes of LBP during pregnancy 25 2.7.1 Hyperlordosis 26 2.7.2 Hormonal changes 27 2.7.3 Muscle insufficiency 27 2.7.4 Changes in total body water content 28 2.7.5 Vascular changes 28 2.8 Risk factors for LBP 29 2.9 Studies examining the biomechanical factors related to LBP 32 2.9.1 Studies examining external loads, postures and spinal 32 loading 2.9.2 Studies examining lumbar curve and centre of pressure 32 during pregnancy 2.10 Studies examining the effects of maternity support belts on 34 LBP during pregnancy 2.11 Physiological and psychological changes during pregnancy 38 2.11.1 Weight gain and abdominal enlargement 38 2.11.2 Skin 39 2.11.3 Postural alteration and decreased mobility 39 2.11.4 Body image 40 2.12 Current use of maternity support garments 40 2.12.1 Types of maternity support garments 40 2.12.2 Fabrications of maternity support garments 42 2.13 Mechanical/biomechanical effect of maternity support belts 44 2.14 Design criteria or standards 45 2.15 Comfort issues in maternity support garments 46 2.16 Health issues in maternity support garments 48 2.17 Aesthetics issues in maternity support garments 48 2.18 Compliance issues in garment therapy 49 2.19 Physiological effects of intimate apparel 50 2.20 Design frameworks 51 2.21 Summary and conclusions of literature review 53
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CHAPTER 3 THE RELATIONSHIPS AMONG BIOMECHANICAL MEASURES DURING PREGNANCY: A LONGITUDINAL STUDY
3.1 Introduction 54 3.2 Methods 54 3.2.1 Study population 54 3.2.2 Pain assessment 55 3.2.3 Biomechanical measures 55 3.2.3.1 Body weight (BW) and body mass index 55 (BMI) 3.2.3.2 Sagittal abdominal diameter (SAD) 56 3.2.3.3 Sagittal lumbar curvature (SLC) 56 3.2.3.4 Centre of pressure during natural stance 57 (COPN) 3.2.3.5 Centre of pressure with lumbar reference 58 (COPL) 3.2.4 Data Analysis 59 3.3 Results 59 3.3.1 Demographics 59 3.3.2 Pain intensity 59 3.3.3 Biomechanical measures 61 3.3.4 Correlation among the biomechanical parameters 64 3.4 Discussion 67 3.5 Conclusions 71
CHAPTER 4 GARMENT NEEDS OF PREGNANT WOMEN BASED ON CONTENT ANALYSIS OF IN-DEPTH INTERVIEWS
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4.1 Introduction 72 4.2 Methods 72 4.2.1 Qualitative approach 72 4.2.2 Study sample 73 4.2.3 Data collection procedure 73 4.2.4 Validity and reliability 74 4.2.5 Data analysis 76 4.3 Results 76 4.3.1 Effective function 79 4.3.2 Safety 81 4.3.3 Skin comfort 82 4.3.4 Ease to put on and take off 83 4.3.5 Aesthetics 84 4.3.6 Functional and aesthetical needs 86 4.4 Discussion 88 4.4.1 Effective function 89 4.4.2 Safety 89 4.4.3 Skin comfort 90 4.4.4 Ease to put on and take off 90 4.4.5 Aesthetics 91 4.4.6 Functional and aesthetical needs 92 4.5 Conclusion 92
CHAPTER 5 COMFORT EVALUATION OF MATERNITY SUPPORT GARMENTS - A WEAR TRIAL AND MATERIAL TESTS
5.1 Introduction 93 5.2 Methods 93 5.2.1 Garment samples 93 5.2.2 Subjects 94 5.2.3 Wear trial procedure 95
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5.2.4 Comfort evaluation 95 5.2.5 Magnitude scaling 96 5.2.6 Internal consistency 97 5.2.7 Data analysis 98 5.3 Results 98 5.3.1 Demographic data 98 5.3.2 Magnitude scaling 98 5.3.3 Thermophysiological comfort 99 5.3.4 Sensory/tactile comfort 100 5.3.5 Comfort during movement 102 5.3.6 Overall comfort 104 5.4 Discussion 106 5.4.1 Thermophysiological comfort 106 5.4.2 Sensory/tactile comfort 109 5.4.3 Comfort during movement 110 5.4.4 Overall comfort 112 5.5 Conclusion 112
CHAPTER 6 DEVELOPMENT OF DESIGN CRITERIA AND GARMENT PROTOTYPE
6.1 Introduction 114 6.2 Design model 114 6.3 Design criteria 116 6.4 Fabric tests and selection 122 6.5 Prototype design and development 130 6.5.1 Style design 132 6.5.2 Pattern design 134 6.5.3 Details of each component and materials used in the 138 final prototype a Front bodice 139 b Front cradle 139
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c Shoulder straps 140 d Back panel 141 e Side panel 141 f Velcro tape 141 g Plastic fasteners 142 h Back belt 142 6.5.4 Seam and stitch types 143 6.6 Evaluation of prototype 143 6.6.1 Clothing and textiles experts’ opinions 148 a Supportive function 148 b Comfort 148 c Aesthetics 149 6.6.2 Subject’s feedback 149 a Supportive function 149 b Comfort 150 c Ease to put on and take off 150 d Safety 150 e Aesthetics 151 6.6.3 Manufacturing challenges 151 6.7 Conclusion 151
CHAPTER 7 CLINICAL TRIAL – A PILOT STUDY
7.1 Introduction 153 7.2 Methods 153 7.2.1 Study design 153 7.2.2 Study population 154 7.2.3 Interventions 157 7.2.4 Outcome measurements 157
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7.2.6.1 Intervention feasibility and comfort 157 evaluation 7.2.6.2 Pain measures 158 7.2.6.3 Biomechanical measures 160 7.2.6.4 Pregnancy outcomes 160 7.2.5 Procedure 161 7.2.6 Data analysis 163 7.3 Results 163 7.3.1 Overall acceptance and satisfaction, compliance and 165 retention rates, and comfort evaluation 7.3.2 Pain intensity, functional status and global 166 improvement 7.3.3 Biomechanical measures 169 7.3.4 Pregnancy outcomes 170 7.4 Discussion 170 7.5 Conclusion 173
CHAPTER 8 CONCLUSION
8.1 The research problems 174 8.2 Research aims and methods 174 8.3 Highlights of research findings 175 8.4 Significance and contribution of the study 177 8.5 Limitations of the study and future research 177
APPENDICES 179 REFERENCES 199
xiii LIST OF FIGURES Figure Description Page 1.1 Outline of methods 6 2.1 Sciatic nerve extends down the posterior aspect of the 11 right buttock to the toe 2.2 Typical pain distributions of PLBP and PPP 12 2.3 Schematic diagram of the Gate Control Theory 14 2.4 Anterior and lateral views of the spine 15 2.5 Anterior view of a female pelvis 16 2.6 Abdominal muscles 18 2.7 Superficial back muscles 19 2.8 Pelvic floor muscles 20 2.9 Deep back muscle 21 2.10 Spinal ligaments 22 2.11 Hyperlordosis during pregnancy 26 2.12 Risk factors for LBP 31 2.13 Types of maternity support garments 41 2.14 Types of fasteners designed for maternity support 43 garments 3.1a Spinal gauge for the measurement of sagittal lumbar 56 curvature 3.1b Sagittal lumbar curvature defined by angle θ 56 3.2a The centre of pressure platform with four load cells 58 (LC) located at the corners 3.2b The position assumed during centre of pressure 58 measurements 3.2c The schematic diagram of the centre of pressure 58 measuring system 3.3 External forces acting on the gestational woman 62 3.4 Estimated centre of mass to determine additional 63 flexion moments 3.5 Relationship between the means of sagittal abdominal 64 depth and body mass index during the three trimesters
xiv (n = 29) 3.6 Effect of pregnancy on centre of pressure shift and the 65 compensatory response of centre of pressure shift (n = 29) 3.7 Relationship between the means of centre of pressure 66 during natural stance and centre of pressure with lumbar reference during the three trimesters (n = 29) 4.1 Commercially-available maternity support garment 75 samples showing the descriptions and the front (left) and back (right) views worn on a dummy 4.2 Participants’ responses in ranking the order of 87 precedence when using or buying maternity support garments 5.1 Mean (S.D.) comfort scores of heat and moisture 99 transfer 5.2 Scatter plot for the mean scores of material appearance 101 and handfeel (n=107) 5.3 Mean (S.D.) comfort scores during the six specified 102 activities 5.4 Mean (S.D.) comfort scores of ease to put on, take off 103 and convenience for toileting 5.5 Overall mean comfort scores of each maternity 104 garment sample 5.6 Mean comfort scores of each assessment item of the 105 brief samples 6.1 Three cycles of elongation test on a fabric specimen 123 6.2 Garment design concepts 130 6.3 Garment design sketches 131 6.4 Technical sketch of the first garment prototype 133 6.5 Technical sketch of the final garment prototype 133 6.6 Pattern shape of the first prototype 135 6.7 Grain lines of the back panel 136 6.8 Pattern shape of the final prototype 137
xv 6.9 The garment prototype for clinical trials 147 7.1 Study design 154 7.2 Summary of recruitment, randomization, and loss to 156 follow 7.3 The procedure for the pilot study 162 7.4 Comfort evaluation scores of maternity support vest 166 and Garment D 7.5 Mean (SD) of pain intensity and Roland-Morris 167 Disability Questionnaire scores between the intervention and control groups 7.6 The percentage of global improvement 168
xvi LIST OF TABLES Table Description Page 2.1 Varying strength of evidence in the risk factors for LBP 30 during pregnancy 2.2 Review of clinical trials related to maternity support belts 35 2.3 Existing product development and design frameworks 52 from clothing literature 3.1 Demographic and clinical characteristics of the subjects 60 (n=29) 3.2 Clinical presentation of the subjects who experienced 60 PLBP 3.3 Significance level of changes of various biomechanical 61 measures with time using one-way repeated measures ANOVA (n = 29) 4.1 Percentage of participants expressed their 78 needs/concerns/problems in using maternity support garment (n = 10) 4.2 Functional and aesthetical values of maternity support 87 garments 5.1 Mean scores of sensory/tactile comfort 100 5.2 Spearman’s correlation matrix of sensory/tactile comfort 101 (n = 105) 5.3 Fabric properties of maternity support garment samples 108 6.1 Design process based on DeJonge’s framework 115 6.2 Design criteria and specifications for the new maternity 117 support garments 6.3 Standard test methods for fabrics 123 6.4 The physical and mechanical properties of tested fabrics 126 6.5 The layers, materials and seam constructions of each 138 component 6.6 A close-up of the amendments made in samples 1 to 4 144 7.1 The timeline of outcome measures assessment 159 7.2 Demographic and clinical characteristics of the subjects 164
xvii in the intervention and control groups (n = 9) 7.3 Biomechanical data of the intervention and control 169 groups at baseline and week 7 (n = 9) 7.4 Pregnancy outcomes of the intervention and control 170 groups (n = 9)
xviii LIST OF APPENDICES Appendix Description Page
1 Information sheet (Biomechanical study) – English 179 version 2 Information sheet (Biomechanical study) – Chinese 180 version 3 Information sheet (Semi-structured interview) – 181 English version 4 Information sheet (Semi-structured interview) – 182 Chinese version 5 Information sheet (Wear trial) – English version 183 6 Information sheet (Wear trial) – Chinese version 184 7 Information sheet (Clinical trial) – English version 185 8 Information sheet (Clinical trial) – Chinese version 186 9 Consent form – English version 187 10 Consent form – Chinese version 188 11 Demographic questionnaire – English version 189 12 Demographic questionnaire – Chinese version 191 13 Numeric Rating Scale (NRS) – English and Chinese 193 versions 14 Roland-Morris Disability Questionnaire – English 194 version 15 Roland-Morris Disability Questionnaire – Chinese 195 version 16 Interview guide 196 17 Wear trial evaluation questionnaire – English 197 version 18 Wear trial evaluation questionnaire – Chinese 198 version
xix ABBREVIATIONS A Sagittal abdominal depth in the first trimester AATCC American Association of Textile Chemists and Colorists A/D Analogue-to-digital ASTM American Society for Testing and Materials BMI Body mass index BW Body weight cc Cubic centimeter cm Centimeter CNS Central nervous system COP Centre of pressure COPN Centre of pressure during natural stance COPL Centre of pressure with lumbar reference CS Caesarean section d Distance FHR Fetal heart rate g Gram GCT Gate Control Theory IASP International Association for the Study of Pain ICC Intraclass correlation coefficient kg Kilogram L Large-diameter LBP Low back pain LC Load cells
Li Half of the distance of the sagittal abdominal depth anterior to the spine centre in the ith trimester L5-S1 The Lumbosacral Joint Mi Moments at the ith trimester mm Millimeter MMT Moisture Management Tester MVA Maximum voluntary action m2 Metres2 Nm Newton meter
xx NRS Numeric Rating Scale NSD Normal spontaneous delivery OMMC Overall moisture management capacity Para Parity PLBP Pregnancy-related low back pain PPP Pregnancy-related pelvic girdle pain QMH Queen Mary Hospital RMDQ Roland-Morris Disability Questionnaire S Small-diameter SAD Sagittal abdominal depth SD Standard deviation sec Second SG Substantia gelatinosa SIJ Sacroiliac joint SLC Sagittal lumbar curvature SLRT Straight leg raise test T Transmission cells th Ti i trimester VAS Visual Analogue Scale VRS Verbal Rating Scale WHO World Health Organization th Wi Body weight gain in the i trimester
xxi CHAPTER 1 INTRODUCTION
1.1 Background
1.1.1 Prevalence and significance of low back pain (LBP)
Low back pain (LBP) is among the most common conditions for which general patients seek medical care (Manek & MacGregor, 2005). Eight of every ten people experience LBP at some point in their lives (Walker, 2000) with peak prevalence between 45 and 60 years of age (Borenstein, 1997; Dionne et al., 2001). Fortunately, most LBP episodes are mild and that 90% of all nonspecific LBP will resolve within three months, either spontaneously or with a pain becomes chronic (Truchon & Fillion, 2000), and in the year following a first episode of LBP, the pain recurs in 60-80% of patients (Troup et al., 1981). The problem of LBP has substantial economic consequences in terms of healthcare resources relating to the treatment and lost productivity. The annual cost has been estimated to be US $91 billion for healthcare expenditures incurred by patients with LBP in the United States alone (Luo et al., 2004).
The odds ratio for women to have LBP varies between 1.30 to 1.57, which has been consistently shown in community-based surveys (Houtman et al., 1994; Skovron et al., 1994). 10-25% of women with chronic LBP reported the first symptom of back pain during pregnancy (Biering-Sorensen, 1983; Svensson et al., 1990). The risk of back pain increases by twofold for women with back pain history and increases for women who have been pregnant before (Ostgaard & Andersson, 1991). During pregnancy, LBP is by far the most common musculoskeletal problem affecting women. Approximately 50% to 80% of pregnant women complain of some form of low back pain, pregnancy-related
1 low back pain (PLBP) and/or pregnancy-related pelvic girdle pain (PPP) (Berg et al., 1988; Mogren & Pohjanen, 2005; Ostgaard et al., 1991; Wang et al., 2004). The pain symptoms often interfere with work, daily activities, and sleep (Jensen et al., 2000; Noren et al., 2002; Wang et al., 2004). Some women may be affected to the extent of disability requiring the use of crutches, wheelchairs, and may even become bedridden (van Zwienen et al., 2004; Wu et al., 2004). The total cost of back pain–related sick leave for pregnant women was estimated to be U.S. $2.5 billion per year in a Swedish study (Noren et al., 1997).
1.1.2 Maternity support belt for relieving LBP during pregnancy
The current pain relief strategies for LBP during pregnancy include avoiding certain physical activities (climbing stairs, standing/walking for long periods), brief rests, low-heeled shoes, heat application, the use of an Ozzlo pillow (a specially-shaped pillow to fit under the woman's abdomen), exercise, ergonomic advice, pelvic support belt, physiotherapy, water gymnastics, pain medication, acupuncture, massage, relaxation, yoga, and chiropractic treatment (Banerud et al., 1992; Heckman & Sassard, 1994; Kihlstrand et al., 1999; Lisi, 2006; Ostgaard et al., 1994b; Perkins et al., 1998; Ritchie, 2003; Stuge et al., 2003; Wang et al., 2005; Young & Jewell, 2002). Among the wide range of preventive and therapeutic interventions, lumbar/pelvic supports are frequently recommended in the management of related lumbar/pelvic pain symptoms experienced by pregnant women (Borg-Stein et al., 2005; Heckman & Sassard, 1994; Perkins et al., 1998; Ritchie, 2003). A US study of 950 pregnant women showed that a support belt was one of the five alternative treatments most frequently recommended by prenatal healthcare providers (Wang et al., 2005).
Pregnant women have reported reduction of PLBP and/or PPP in some studies which examined the effects of wearing support belts in conjunction with other interventions (Elden et al., 2005; Kvorning et al., 2004; Noren et al., 1997; Wedenberg et al., 2000). However, limited information was provided on the
2 effectiveness of belt usage alone (Ostgaard et al., 1994b) as it is impossible to single out the belt wearing effect from the other treatments (Elden et al., 2005; Kvorning et al., 2004; Mens et al., 2000; Nilsson-Wikmar et al., 2005; Noren et al., 1997; Wedenberg et al., 2000). Only a few studies have investigated the effects of wearing a maternity support belt on PLBP and/or PPP independent of other treatments (Carr, 2003; Depledge et al., 2005; Ostgaard et al., 1994b). Thus, there is a lack research evidence to demonstrate the effectiveness of wearing of maternity support garment in the prevention and treatment of PLBP and/or PPP.
Treatments for LBP during pregnancy such as exercises, ergonomic education, and support belt generally aim at maintaining good postural alignment (Fast, 2003). Recent studies have shown that the pelvic support belt provides a stabilization effect to the lumbopelvic structures (Damen et al., 2002; Mens et al., 2006). However, no objective measure has been used to guide the treatment and to evaluate the rehabilitation progress of LBP.
Clinicians have reported that in some patients, the belt even led to increased pain and needed to be removed (Mens et al., 1996). A study reported a few isolated fetal heart rate decelerations after wearing a maternity support belt for 20 minutes (Beaty et al., 1999), which were not attributable to the support. However, no studies have been conducted to examine the long term wearing effect on maternal and fetal health outcomes. Studies have also found that the maternity support belts have several undesirable effects including skin irritation, discomfort during movement, and inconvenience when using the toilet (Carr, 2003; Weber et al., 1972). These reports raise the issues of comfort and health in the use of these close fitting garments.
1.1.3 Existing maternity support garments
Maternity support garments can be categorized into four main types: belts, briefs, cradles and torso supports. These garments having various designs are readily
3 available in the commercial market and widely advocated to pregnant women owing to a large body of anecdotal evidence of the effectiveness of such garments in terms of pain relief and correction of hyperlordosis. In both Western and Asian cultures, maternity support belts have traditionally been worn for back support and comfort (Carr, 2003). Specific reference to wearing a maternity lumbosacral support dates as far back as 12th century Asian (Weber et al., 1972). To date, numerous maternity support garments have been developed and patented, including 32 patents from the United States, 19 from Japan, and 15 from Europe (Ho et al., 2006). However, no research data was found relating to the design criteria of therapeutic functional garment.
1.2 Statement of the problems
In short, maternity support garments are often worn by many women to manage LBP during pregnancy however the effectiveness, comfort, and health of these garments are still great issues of concern. There is a lack of research relating to the garment design and the effectiveness in the relief of LBP during pregnancy. Furthermore, the mechanistic action of these garments is not fully understood as there is limited objective evidence to substantiate its putative beneficial effects of pain relief and postural improvement.
This underlies the urgent need for extensive research and controlled trials to support or refute the use of maternity support garment as an adjunct therapy for the relief of LBP during pregnancy since “Answering fundamental questions about efficacy, safety, appropriate clinical applications, and meaningful outcomes for all medical therapies, including those considered alternative medicine, requires critical and objective assessment using accepted principles of scientific investigations and rigorous standards for evaluation of scientific evidence” (Fontanarosa & Lundberg, 1998).
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1.3 Objectives of this study
The aims of this study are twofold: 1). to develop the design criteria and prototypes of maternity support garments using multidisciplinary and scientific approaches and 2). to evaluate the feasibility of the garment prototype in a pilot clinical study.
Specific objectives include: a. To examine the biomechanical changes of a sample of Chinese women during the three trimesters of pregnancy (Study I) b. To investigate the physical and psychological needs of a sample of pregnant Chinese women with LBP when using maternity support garments (Study II) c. To evaluate the wearers’ comfort responses in maternity support garments and to determine the garment characteristics that influence wear comfort (Study III) d. To develop the design criteria for the production of a therapeutic garment to support the abdomen and back with physical comfort, and taking into account aesthetic concerns (Studies II & III) e. To determine the feasibility of the new garment prototype in future clinical trials (Study IV) f. To assess the acceptance and compliance of garment prototype (Study IV)
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1.4 Research Methods
Based on DeJonge’s design framework, this study was conducted in three phases: a) an exploratory phase, b) a developmental phase, and c) an evaluative phase (Figure 1.1). In the exploratory phase, a longitudinal study (Study I) of 29 pregnant women was undertaken to determine the key biomechanical measures for evaluating the biomechanical effects of a maternity support garment so as to specify its functional requirements. In-depth interviews (Study II) with 10 pregnant women and wear trials (Study IIIa) by 14 subjects were conducted to elicit users’ responses on 8 maternity support garments in terms of physical and psychological comfort. Fabric measurements of physical properties (Study IIIb) were analyzed on the same 8 tested garments to provide detailed objective design specifications for the selection of suitable materials in making the first garment prototype.
Exploratory Developmental Experimental Phase Phase Phase
Study I: DeJonge’s framework Biomechanical study
Study II: Schematic Interviews designs Study IV: Pilot study
Study IIIa: Design Material testing Garment prototype principles Wear trials & selection Conclusion
Study IIIb: Prototype Material tests design & evaluation
Figure 1.1 Outline of methods
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In the developmental phase, after the consideration of the results from the interviews, wear trials and material tests, a set of comprehensive functional garment design criteria was developed. A new prototype was made according to the garment needs revealed from the interviews, the desired garment attributes found in the wear trials, and the material properties specified. The design process proceeded from brainstorming, to consolidation, to schematic designs that led to physical garment prototype samples produced with technical considerations. For the selection of appropriate materials to be used for the garment prototypes, 16 alternative fabric samples were tested for consideration.
In the evaluative phase, the garment prototype was assessed in a pilot clinical study (Study IV) on 9 pregnant women with pregnancy-related low back pain between gestational weeks 29-36. Pain intensity, functional status, and biomechanical measures of centre of pressure and sagittal lumbar curve were determined. Obstetric outcomes and fetal status were also assessed.
1.5 Significance of the study
This study on maternity support garment not only serves as new knowledge for promotion of women’s health, but also contributes to a new scientific basis for future garment design for medical use. The methodologies used in the interviews, wear trials, biomechanical studies, prototyping and clinical trials serve as useful research tools and models for the product development and evaluation of other functional garments.
1.6 Assumption
Because pain is a highly subjective and personal experience (Melzack & Wall, 1996), it is assumed to be present according to the individual’s own experiences, and it exists whenever (he or) she says it does (McCaffery & Beebe, 1989).
7 1.7 Delimitations
This study examined only singleton pregnancies; twins or multi-fetal pregnancies were not included as the increased anterior loading may have varying effects on the biomechanical factors during pregnancy and in the use of garment therapy. This study was confined to women who experienced LBP only during pregnancy. Those with chronic LBP prior to pregnancy were excluded as it would introduce factors of spinal diseases or injuries, which are beyond the scope of this research.
1.8 Organization of thesis
This thesis is divided into eight distinct chapters. Chapter 1 briefly introduces the background, scope and objectives of the study. The methods and significance of the study are delineated. Chapter 2 reviews the current literature on LBP during pregnancy and the existing maternity support garment by highlighting the clinical presentation, etiologic theories, garment designs and proposed mechanistic action. Included in this review are discussions of the physical and psychological changes during pregnancy, design criteria and frameworks, and the converging lines of research related to LBP in the biomechanical perspective, and studies relating to garment treatments.
Chapter 3 describes the longitudinal study that examined six biomechanical measures and their relationships among 29 pregnant women. Chapter 4 presents the in-depth interviews and the five main themes of garment needs generated from the interview data. Chapter 5 reports the wear trials in the evaluation of comfort responses on 8 different maternity support garments and the physical fabric properties. In Chapter 6, the development design criteria and the garment prototype are presented. Chapter 7 discusses the aims, methods and results of the pilot clinical study of the final garment prototype. Finally, Chapter 8 delineates the implications and limitations of the current study, and recommendations are made for future research work.
8
The outline of this study was presented in The 4th International Conference and Exhibition on Healthcare and Medical Textiles, Bolton, UK (16 -18 July 2007).
9 CHAPTER 2 LITERATURE REVIEW
2.1 Introduction
In this chapter, a brief introduction will be presented on the definitions and theories of pain, the anatomy of lumbar spine and pelvis, the clinical presentations, causes and risk factors of pregnancy-related low back pain and pelvic girdle pain. Next, a critical review of studies examining the biomechanical factors related to LBP and the effect of maternity support belts will be highlighted. Then the current use and types of maternity support garments, their mechanistic actions and garment-related problems will be discussed in details. This chapter also includes the literature in the areas of the physiological and psychological changes during pregnancy, the physiological effects of intimate apparel as well as the design criteria and frameworks will be reviewed. Finally, the purpose and justification of this study will be highlighted.
2.2 Terms and definitions of LBP
Before reviewing the literature, clarification of two terms is necessary and they are: a). low back pain and b). low back pain during pregnancy. a). “Low back pain (LBP)” generally refers to acute or chronic pain located in the lumbar or posterior pelvic region with or without sciatica among the general population (National Institute of Occupational Safety and Health, 1994). Acute LBP is often defined by pain of less than 6 weeks duration and characterized by a sudden onset; subacute LBP is pain of 6 to 12 weeks and chronic LBP lasts for 12 weeks or more and is of gradual onset (Loeser, 2001). Sciatica is characterized by unilateral radiating leg pain below the knee in a dermatomal distribution along the sciatic nerve (Figure 2.1) which
10 may be accompanied by sensory symptoms such as numbness and tingling (Koes et al., 2007).
Figure 2.1 Sciatic nerve extends down the posterior aspect of the right buttock to the toes (Source: http://adam.about.com/encyclopedia/Sciatic- nerve.htm?once=true&)
b). “LBP during pregnancy” refers to pregnancy-related low back pain (PLBP) and/or pregnancy-related pelvic girdle pain (PPP) (Figure 2.2). Although PLBP and PPP are evidently different as described below in the clinical presentation section and require different treatments, PLBP was not clearly distinguished from PPP in the earlier literature. It is therefore inevitable that some literature being reviewed may not be entirely clear as to which condition it is referring to, since both conditions were described together as if it were a single entity.
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Figure 2.2 Typical pain distributions (shaded areas) of PLBP (A) and PPP (B) (Source: Perkins et al., 1998, p.333)
It is important to note that this study focuses on PLBP rather PPP. Therefore, this thesis will use the terms “PLBP” and “PPP” specifically if these conditions have been clearly defined in the article, otherwise the term “LBP during pregnancy” is used to include PLBP, PPP, or PLBP and PPP combined.
2.3 Definition of pain
While we all have experienced pain at some point in our lives, finding a definition that can fully embrace what pain is has been a great challenge to pain researchers because pain is complex and multidimensional. Early definitions focused on the mechanistic nature of pain as deeply influenced by Descartes’ concept of pain system, with the perception of a straight channel that begins in the skin and terminates in the brain (Melzack & Wall, 1996). With the evolution of new pain theories, the definition of pain has been broadened. The International Association of the Study of Pain (IASP) defines pain as “an unpleasant sensory and emotional experience associated
12 with actual or potential tissue damage, or described in terms of such damage” (Merskey & Bogduk, 1994). This definition is widely accepted by most pain researchers as it delinks from firm association between and tissue damage, and it adds the emotional dimension which supplements the previously lacking components in the definition (Melzack & Wall, 1996).
2.4 Gate Control Theory (GCT)
The Gate Control Theory (GCT) of pain was first proposed by Melzack and Wall (1965) (Melzack & Wall, 1965). It is now widely accepted as the classical pain theory and has greatly advanced pain research (Horn & Munafo, 1997). In the GCT, pain is not a result of direct transmission of neural impulses from the pain receptor neurons of the skin to the brain, as suggested by Descartes but rather, pain perception is modulated by interaction between different neurons. Melzack and Wall exemplified the active role of the brain or cognitive process as opposed to a passive receptive role. According to the GCT, the nociceptive signals that travel from the periphery to the central nervous system (CNS) are modulated by a neural mechanism called the ‘gate’ (Figure 2.3). This “gate” is proposed to be situated in the substantia gelatinosa (SG) at the dorsal horn of the spinal cord.
The opening or closing of this hypothetical gate is determined by the amount of excitatory activity in small-diameter (S) and large-diameter (L) nerve fibers. S (A-delta and C) and L (A-beta) nerve fibers project to the SG and converge into the first central transmission cells (T) in the dorsal horns. The activity in the S nerve fibers will enhance the neural transmission by opening the gate, while activity in the L nerve fibers has an inhibitory effect by closing the gate. A schematic diagram of the GCT (Figure 2.3) presented below shows that the inhibitory effect exerted by the SG on afferent nerve fibers is increased by activities in the L nerve fibers and decreased by activities in the S nerve fibers.
13
+ = excitation; – = inhibition
Figure 2.3 Schematic diagram of the Gate Control Theory (Source:
Melzack and Wall, 1965, p. 971)
It is well documented that cognitive or higher central system processes such as anxiety, memory, anticipation and past experience are able to enhance the transmission by opening the gate. In contrast, medication, relaxation, concentration on other stimuli, touch and massage can inhibit the transmission by closing the gate (Melzack & Wall, 1996). In sum, pain is a complex modulation of neuronal impulses through inhibitory and excitatory pathways.
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2.5 Relevant anatomy of the lumbar spine and pelvis
For a better understanding of the literature, relevant anatomy of the lumbar spine and pelvis are presented in the next section and are highlighted in the diagrams with bolded characters. There are four regions in the human spine: the cervical (neck), thoracic (chest/trunk), lumbar (low back) and sacral (pelvic) regions (Figure 2.4).
Figure 2.4 Anterior and lateral views of the spine (Source: The McGraw-Hill Companies)
15 The spine, also called the vertebral or spinal column, is composed of seven cervical vertebrae, twelve thoracic vertebrae, and five lumbar vertebrae. The lumbar spine is situated on top of the sacrum, which is formed by five vertebrae naturally fused together into a solid unit. The sacrum is wedged between the ilium and connects the spine to the pelvis (Figure 2.5). At the end of the spinal column is the coccyx (tailbone).
Figure 2.5 Anterior view of a female pelvis (pelvic girdle) (Source: The McGraw-Hill Companies)
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2.5.1 Natural spinal curves
There are four natural curves in the vertebral column. The cervical lordosis curves toward the back of the neck, and the thoracic kyphosis curves toward the front of the chest. The lumbar lordosis curves toward the back and the anterior sacral convex curve curves toward the belly or pelvic region (Figure 2.4).
2.5.2 Sacroiliac joint
The sacroiliac joints (SIJ) (Figure 2.5) are where the sacrum meets the iliac bones on each side. The SIJ has both synovial joint portion (like the knee) and a fibrous joint. The joint surfaces are irregular so that the bones form an almost interlocking construct, allowing for only limited motion during weight bearing and forward flexion.
2.5.3 Vertebra
Each vertebra has unique features depending on the region in which it is situated. Regardless of location, it has three basic functional parts: a). the drum-shaped vertebral body, designed to bear weight and withstand compression or loading; b). the posterior arch, consisted of the lamina, pedicles, and facet joints; and c). the transverse processes, serve as points of attachment for muscles and ligaments in the spine (Figure 2.4). The lumbar spine has the largest vertebrae (in diameter) of the spine since the lumbar vertebral bodies are the weight-bearing portion of the spine.
2.5.4 Global spinal muscles
Trunk muscles are categorized into global or local muscle systems depending on their main mechanical roles in stabilization (Bergmark, 1989). The global muscle system of the spine consists of large torque producing muscles that act on the trunk, spine and pelvis without direct vertebral
17 attachments such as rectus abdominis, transversus abdominis, internal oblique, external oblique, erector spinae, and pelvic floor muscles (Figures 2.6, 2.7 and 2.8) (Preuss & Fung, 2003). These global muscles provide the bulk of the stiffness to the spinal column as a whole (Cholewicki & McGill, 1996).
Figure 2.6 Abdominal muscles
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Figure 2.7 Superficial back muscles (Source: http://www.hyperionics.com)
19
Figure 2.8 Pelvic floor muscles (Source: http://en.wikipedia.org/wiki/Image:Gray404.png#file)
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2.5.5 Local spinal muscles
The local muscle system comprises deep muscles attached directly to the lumbar spine and individual vertebra such as multifidus to provide stiffness to the spine as a whole and at the segmental level (Figure 2.9). In order to meet both the equilibrium and stability requirements of the lumbar spine, a balance must be met between the activity of the large global muscles, and that of the smaller local muscles (Bergmark, 1989; Cholewicki & McGill, 1996).
Figure 2.9 Deep back muscles (Source: http://www.etsu.edu/cpah/hsci/forsman/DeepBackMuscles4Complete.htm)
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2.5.6 Spinal ligaments
The ligaments of the spine are fibrous tissues that keep the bones and joints in alignment (Figure 2.10). These ligaments can stretch or break, causing pain. A partial or complete tear of a ligament is called a sprain.
Figure 2.10 Spinal ligaments (Source: http://www.spineuniverse.com/displayarticle.php/article1268.html)
22 Having understood the basic structures of the spine including the spinal column, natural curves, bones, joints, muscles and ligaments, we will move on to the clinical presentations of LBP during pregnancy.
2.6 Clinical presentation of PLBP and PPP
Experts in the field are in general agreement that there are two main types of LBP during pregnancy: pregnancy-related low back pain (PLBP) and pregnancy-related pelvic girdle pain (PPP) (Ostgaard, 1996; Ostgaard, 1997b; Wu et al., 2004). The clinical presentations of PLBP and PPP in terms of the location and nature of pain are highlighted in the next sections. Then, the prevalence, onset, intensity and impact of pain are presented.
2.6.1 Pregnancy-related low back pain (PLBP)
PLBP can be defined as pain that occurs over the area of the lumbar spine and above the sacrum, which may or may not be concurrent with sciatica (Figures 2.1 and 2.2a) and its clinical presentation similar to that of LBP experienced by women who are not pregnant (Ostgaard et al., 1994a; Ostgaard et al., 1996). Tenderness may be present in the muscles along the spine during the episodes of pain. PLBP is more consistent in site and nature compared to PPP. Pain in the low back is often described as a dull ache. It has also been reported to be “shooting”, a “feeling of oppression”, and both a “sharp twinge” and “dull” pain (Hansen et al., 1999). The pain typically increases with adopting the same posture for prolonged periods such as sitting and standing.
2.6.2 Pregnancy-related pelvic girdle pain (PPP)
PPP can be defined as pain mostly experienced between the posterior iliac crest and the gluteal fold (Figure 2.2b). The pain may radiate to the upper portion of the posterior thighs, and does not usually radiate below the knees. PPP is difficult to localize (Albert et al., 2000) and tends to fluctuate and change in location during the course of pregnancy (Kristiansson et al., 1996).
23 It often involves unilateral or bilateral pain deep in the gluteal region distal and lateral to the L5-S1 vertebrae; in the sacroiliac joints and posterior superior iliac spine area; and the pain can also be felt in the region of the public symphysis and coccyx (Figure 2.5) (Albert et al., 2002; Gutke et al., 2006; Ostgaard et al., 1994a; Ostgaard et al., 1996). Pain over the sacrum (central) and coccyx is very common especially when the fetal head engages as it presses against the pelvic girdle and stretching forces are caused by fetal position, weight, and movements.
The pain has been described as ‘stabbing’ and morning stiffness may also be present. Women have reported a ‘catching’ sensation in their upper leg when walking. PPP can be exacerbated by rolling in bed, climbing stairs, sitting and rising from a seated position, lifting, twisting, bending forward, and walking. The pain does not quickly resolve with rest. PPP can be differentiated from healthy subjects by the straight leg raise test (SLRT) (Mens et al., 1999; Mens et al., 2001; Mens et al., 2006), while 15 physical tests can be performed to classify the subgroups of PPP (Albert et al., 2000).
2.6.3 Prevalence, onset, pain intensity and impact of PLBP and PPP
The above mentioned review also showed that about 50% of the cases are PPP, about 33% are PLBP and 17% are both combined (Wu et al., 2004). The onset of pain can begin as early as 8-12 weeks into pregnancy, and reaches peak intensity between the 24th and 36th week of pregnancy (Wu et al., 2004). Of all women with PLBP and/or PPP, 45% have mild or quite bearable pain, 30% moderate pain and 25% severe pain with the average intensity of 50mm or 60mm on 100mm Visual Analogue Scale (VAS), which is higher than the average score among patients seeking help for back pain in a back pain clinic (Wu et al., 2004). Pain in PPP was reported to be more intense than in PLBP but the situation is reversed during postpartum (Ostgaard et al., 1996). The pain can interfere with work, daily activities, and sleep (Fast & Hertz, 1992; Hansen et al., 1999; Jensen et al., 2000; Kristiansson et al., 1996; Larsen et al., 1999; Mogren, 2006; Noren et al., 2002; Ostgaard, 1997a; Sydsjo et al., 2001; Wang et al., 2004). Some may
24 be affected to the extent of disability requiring the use of crutches, wheelchair, and may even become bedridden (van Zwienen et al., 2004; Wu et al., 2004). The total cost of back pain–related sick leave for pregnant women was estimated to be U.S. $2.5 billion per year (Noren et al., 1997).
All in all, both PLBP and PPP conditions are highly prevalent and have considerable impact on pregnant women. The clinical presentations of PLBP and PPP vary widely which defines the two distinct entities. This highlights the importance of the differentiation between the two conditions since different conditions vary in the response to treatments including garment therapy.
2.7 Possible causes of LBP during pregnancy
Before discussing the mechanisms of maternity support garments, it is important to understand the etiology of LBP during pregnancy. In the following section, we will highlight the possible causes and the known risk factors. Since this study only concerns PLBP, literature related to LBP with non-specific cause or specific underlying pathology is beyond the scope of this review.
Many different theories have been proposed for the cause of LBP during pregnancy (Daly et al., 1991; MacEvilly & Buggy, 1996; Monaco, 1996; Ritchie, 2003; Rungee, 1993). These include a). hyperlordosis, b). hormonal changes, c).abdominal muscles insufficiency, d). changes in body water content, and e). vascular changes.
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2.7.1 Hyperlordosis
Increasing lumbar lordosis (Figure 2.11) is thought to play a role in causing LBP during pregnancy (Borg-Stein et al., 2005; Daly et al., 1991; Ritchie, 2003). The theory posits that as the gravid uterus enlarges, weight gain is concentrated in the lower two thirds of the trunk causing the centre of gravity to shift anteriorly, which leads to a tendency to fall forward. To restore the centre of gravity, progressive lordosis occurs when the woman unconsciously arches her upper body back over the pelvis and lower extremities (MacEvilly & Buggy, 1996; Monaco, 1996). Hyperlordosis is likely to influence the load distribution in the spine, creating abnormal mechanical stresses and strain on the muscles and ligaments of the lumbar spine and pelvis, which results in pain (Fast, 2003). The rapid weight gain between the 5th and 7th months of pregnancy may also exceed the adaptive capability of the trunk musculature in susceptible individuals (MacEvilly & Buggy, 1996).
Figure 2.11 Hyperlordosis during pregnancy (Source: Ritchie 2003, p.457)
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2.7.2 Hormonal changes
Increased joint laxity due to hormonal changes is suggested to be a causative factor for the pathogenesis of LBP during pregnancy (MacLennan et al., 1986). Altered biomechanics of postural change as described above, in combination with the release of hormones such as relaxin and estrogen, produces ligamentous laxity, which may further increase strain on the lower back and pelvis (Borg-Stein et al., 2005; Daly et al., 1991; Ritchie, 2003). Relaxin, a polypeptide hormone that regulates collagen, softens the strong rigid ligaments around the pelvic joints and cervix in preparation for parturition. Ligamentous laxity rendering less stable pelvic joints may lead to exaggerated range of movement in these joints, which in turn may result in stretching of the structures of capsule and ligaments that are around the pelvic joints and sacroiliac joints (SIJ) (the junction between the sacrum and the ilium) to cause pain as these structures are richly innervated by unmyelinated nerves (MacEvilly & Buggy, 1996; Ostgaard & Andersson, 1992).
Concentrations of relaxin are normally elevated during the 1st trimester, and then decline early in the 2nd trimester to a level that remains stable throughout the rest of the pregnancy (Heckman & Sassard, 1994). The increased levels of relaxin lead to widening of the pubic symphysis by 3-5 mm, and increased mobility of the SIJ, sacrococcygeal joints, and the symphysis pubis (Figure 2.5), which begins in the 10th to 12th week of pregnancy (Goldsmith et al., 1995; Heckman & Sassard, 1994).
2.7.3 Muscle insufficiency
The growing gravid uterus stretches the abdominal muscles which may weaken these muscles and alter the length tension relationship (Fast, 2003). The length and strength of abdominal and paraspinal muscles may also be affected by the lumbar hyperlordosis. Paraspinal muscle strain may be
27 secondary to inefficient function of anterior abdominal wall muscles and play a role in the production of pain (Orvieto et al., 1994).
2.7.4 Changes in total body water content
Fluid retention, particularly in connective tissues around the vertebral column and pelvis, increases laxity around these joints and this may further contribute to the instability of the lumbar spine and pelvic joints (MacEvilly & Buggy, 1996). Mean total body water content is reflected in the fetal amniotic fluid and placenta, and an increased hydration of macromolecules in connective tissue ground substance (MacFayden, 1989). The increased level of estrogen in early pregnancy is initially responsible for the natriuretic effect, which causes the negative sodium balance to induce renin and isorenin release from the uterus. This in turn will lead to production of angiotensin II, subsequent increase in the levels of aldosterone and antidiuretic hormone which resorb sodium and retain water.
2.7.5 Vascular changes
It has been suggested that hypervolemia, combined with vascular changes, leads to obstruction of the vena cava, which may cause pain. The enlarging uterus can apply pressure on the aorta and vena cava, especially between L1 to L5, along with hypervolemia resulting in engorgement of the venous system, especially the extradural veins distal to the occluded zone. Obstruction may increase pressure within the lumbar vertebrae, and increase venous stasis, which may result in hypoxia and metabolic disturbance of unmyelinated nerves and neural structures, leading to back pain (Fast, 2003; Fast & Hertz, 1992).
To summarize, the strain of the ligaments in the pelvis and lower parts of the spine is often assumed to cause pregnancy-related pelvic girdle pain and low back pain, which results from a combination of factor, the most important of which are hormonal effects (Borg-Stein et al., 2005; MacLennan et al., 1986; Ritchie, 2003), altered posture (MacEvilly &
28 Buggy, 1996; Monaco, 1996), muscle weakness (Dempsey et al., 1997; Orvieto et al., 1994), and the increased weight of fetus and uterus (Daly et al., 1991; MacEvilly & Buggy, 1996; Ritchie, 2003). Ligamentous laxity may render mechanical instability which further increase stretch and strain on the pelvis and low back and thus stimulate mechanoreceptors with a nociceptive function leading to pain (Heckman & Sassard, 1994; MacEvilly & Buggy, 1996; Ritchie, 2003). Increase in joint stability or the reduction of joint laxity and mobility would therefore lead to pain reduction.
The above theories pertaining to hyperlordosis, shifting of the centre of gravity, poor body mechanics, and muscle insufficiency summarize the existing background knowledge of the biomechanical theory of LBP during pregnancy. On the basis of these theoretical premises, several biomechanical measures, including the anterior load, centre of pressure and lumbar curve were selected for further investigation in our biomechanical study as described in Chapter 3.
2.8 Risk factors for LBP
Although the etiologic mechanisms for LBP during pregnancy are still not fully known, the risk factors have been identified with various strength of the evidence (Table 2.1) (Wu et al., 2004). Wu et al. (2004) has shown in a review that there is strong evidence for strenuous work, previous LBP, and previous lumbopelvic pain as risk factors of LBP during pregnancy.
29 Table 2.1 Varying strength of evidence in the risk factors for LBP during pregnancy (summarized from Wu et al., 2004, p. 582) Strong Weak Conflicting No Maternal bone Strenuous work Maternal height Maternal age density Number of Previous LBP Maternal weight Previous abortion pregnancy
Previous Fetal weight Maternal ethnicity lumbopelvic pain Oral during/after contraceptives pregnancy
Smoking status Epidural
anesthesia
The National Institute for Occupational Safety and Health reviewed epidemiologic research in relation to musculoskeletal disorders and exposure to physical factors. They also found that previous pain/injury history to the lower back is consistently a strong risk factor for future reports of LBP in the work environment (National Institute of Occupational Safety and Health, 1994). Reviews have highlighted the importance of physical ergonomic work factors and the most frequently cited physical factors include lifting, forceful movement, whole body vibration, and awkward postures (Lotters et al., 2003; Punnett et al., 2005).
Increasing evidence suggested that psychosocial phenomena are also linked to low back problems, although it was less conclusive to date. Included in the domain of job and work environment are various aspects of job content such as perceived workload, monotonous work, low job control, low job satisfaction, and limited social support (Truchon, 2001). Environmental parameters outside work typically include factors associated with demands and responsibilities in the family and during leisure time, and social/familial relationship and support.
30 Individual factors that are associated with LBP in the general population include age, anthropometry, socioeconomic characteristics, smoking habit, physical fitness and strength, psychological factors (for example, anxiety and depression), personality trait, cognitive appraisals and coping strategies (Chany et al., 2006; Dempsey et al., 1997; Truchon, 2001). The complexity of LBP may involve an interactive effect of physical, psychosocial, individual and genetic factors as presented in Figure 2.12.
While LBP during pregnancy is a complex and multifactorial phenomenon, the literature shows that physical or biomechanical factors are believed to strongly influence the risk of the development of LBP and low back disorders. There is a converging line of research related to the risk of LBP, mechanical loading of the spine, the load magnitude, and non-neutral postures, which is discussed in the next section. In view of the strong association between previous LBP and previous lumbopelvic pain during/after pregnancy, these factors were considered as confounding variables which must be controlled in the evaluative phase of this study by stringent selection criteria of including only primagravida in the pilot clinical trial.
Figure 2.12 Risk factors for LBP
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2.9 Studies examining the biomechanical factors related to LBP
2.9.1 Studies examining external loads, postures and spinal loading
There are converging lines of research regarding LBP in non-pregnant subjects. Firstly, an increased load on the lumbar spine due to mechanical forces is associated with increased risks for LBP (Marras et al., 1993; Marras et al., 1995). Secondly, strong in vivo evidence showed that external loads and different spinal postures affected spinal loading (Nachemson, 1966; Sato et al., 1999; Takahashi et al., 2006). Spinal loading increased in both forward and backward bending (Sato et al., 1999), and was higher with external weight than without at any tilting angles (Takahashi et al., 2006). Direct measurement of intradiscal pressure showed a significant positive linear relationship between trunk angle during forward bending and the mechanical load on the lumbar spine. The mean load on the lumbar spine could be increased by approximately 2, 2.5 and 3.5 fold during forward bending at 10, 20 and 30 degrees when compared to upright standing (Takahashi et al., 2006). The increased spinal loading consisted of both external and internal loads. The external load is the weight of the body above the lumbar disc and the internal load is the ligamentous and muscle forces needed to stabilize the spine in different postures (Nachemson, 1966).
2.9.2 Studies examining lumbar curve and centre of pressure during pregnancy
Pregnancy is associated with increased trunk mass, which may lead to postural alteration. Based on the above evidence, pregnant women may have increased spinal loading due to increased anterior load and altered spinal postures, and may ultimately increase the chance of back pain.
32
Studies relating to postural changes during pregnancy have reported changes in lumbar lordosis and the centre of pressure (COP) (Bird et al., 1999; Bullock et al., 1987; DonTigny, 1985; Foti et al., 2000; Fries & Hellebrandt, 1943; Golomer et al., 1991; Moore et al., 1990; Ostgaard et al., 1993; Snijders et al., 1976). However, the role of these postural changes is still inconclusive because of conflicting results and insufficient data. Some investigators found that there was a significant increase in lumbar lordosis (Bullock et al., 1987; Franklin & Conner-Kerr, 1998) whereas others have reported that lumbar lordosis was decreased (Foti et al., 2000; Snijders et al., 1976) or that no significant trend was observed (Gilleard et al., 2002b; Moore et al., 1990; Ostgaard et al., 1993). A few longitudinal studies have investigated the COP during gait analysis and in the mediolateral aspect (Bird et al., 1999; Foti et al., 2000; Golomer et al., 1991). Only one study has examined one pregnant woman in a sagittal plane during natural standing and found significant posterior COP displacement during pregnancy (Fries & Hellebrandt, 1943).
Although the etiology of LBP during pregnancy is still not fully understood, postural changes related to the shifting of centre of gravity have often been postulated as one of the major causes of LBP during pregnancy (Franklin & Conner-Kerr, 1998). However, the above review shows that only a few studies have investigated the biomechanical factors during pregnancy. It is therefore important to understand these biomechanical factors as they may be useful in guiding the treatment and evaluating the rehabilitation progress of LBP during pregnancy as well as providing insights into the design of therapeutic intervention. In the next section, the effects of maternity support belts on LBP during pregnancy are critiqued.
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2.10 Studies examining the effects of maternity support belts on LBP during pregnancy
Only the maternity support belts or binders have been researched into as a preventive or therapeutic measure to manage PLBP and/or PPP and no research data is available on the other three types of maternity support garments. Table 2.2 summarizes the findings of both randomized and nonrandomized clinical trials of maternity support belts in the prevention and/or treatment of PLBP and PPP.
Evidence suggests that the effectiveness of using maternity support belts to reduce pregnancy-related back or pelvic girdle pain remains inconclusive. Few studies have investigated the effect of wearing a maternity support belt on PLBP and/or PPP (Carr, 2003; Depledge et al., 2005; Ostgaard et al., 1994b) and reported pain reduction. Other studies were primarily designed to evaluate the effect of combined treatment (that is, the maternity support belts were worn as a part of the intervention program) (Elden et al., 2005; Haugland et al., 2006; Kvorning et al., 2004; Mens et al., 2000; Nilsson- Wikmar et al., 2005; Noren et al., 1997; Wedenberg et al., 2000) and some were shown to be effective in reducing pain (Elden et al., 2005; Kvorning et al., 2004; Noren et al., 1997; Wedenberg et al., 2000). However, limited information was provided on the efficacies of belt usage and it is impossible to single out the belt wearing effect from the other treatments.
34 Table 2.2 Review of clinical trials related to maternity support belts Study Design Study n Intervention Results population Ostgaard et Quasi-RCT Pregnant women 407 Group A Control Group C had significantly lower pain intensity al. 1994 with or without Group B Group education and exercise compared to Group A at week 8 postpartum. pain, before Group C Individualized education and exercise for Group C had significantly less sick leave week 18. longer periods and exercises at home compared to Group A. 82% of the women with PPP had pain relief Leaflet and 2 classes of modified back school from a non-elastic sacroiliac belt education and training program given to Group B and C. In addition, a non-elastic sacroiliac belt was given to those who had posterior pelvic pain.
Noren et al. Controlled Pregnant women 135 Group A Control: No special intervention (n=81) Group B significantly decrease in pain 1997 trial with LBP or Group B Individualized physiotherapy (n=54) intensity, but no comparison between groups. posterior pelvic Group B had significantly less sick leave days pain or both, Education, exercises, and non-elastic pelvic compared with Group A. between week support belt for those with posterior pelvic pain 11- 36
Mens et al. RCT Women with 44 Group A Control: Refrain from exercises (n=14) No significant difference in the mean change 2000 persistent pelvic Group B Placebo: Training of longitudinal trunk in pain score (VAS) from baseline pain, from 6 muscle exercises (n=14) No significant difference in the mean change weeks to 6 Group C: Training of the diagonal trunk muscle in global improvement and physical mobility months exercises (n=16) postpartum 30 min videotape with information, ergonomic advice and how to use a pelvic belt given to all 3 groups.
(Continued)
35 Table 2.2 (Continued) Review of clinical trials related to maternity support belts Study Design Study n Intervention Results population Wedenberg RCT Pregnant women 60 Group A Group physiotherapy; ten 50 min sessions Group B had significantly lower mean pain et al. 2000 who had LBP, for 6-8 weeks (n=18) scores (VAS) less than week Group B Acupuncture; ten 30 min session for 1 Group B had significantly better functional 32. month (n=28) status compared to Group A.
A pelvic support belt, warmth, massage, soft tissue mobilization were also provided to all the subjects.
Carr 2003 Prospective Pregnant women 40 Group A Control (no back support) (n=10) Group A had significant reduction in mean 2-group with low back Group B Loving Comfort back support (CMO, pain scores and effect of pain on daily design with pain, at least 20 Inc., Barberton, OH) (n=30) activities. repeated weeks of measures gestation
Kvorning et RCT pregnant women 72 Group A No sham stimulation (n=35) 60% in the acupuncture group had decreased al. 2004 reporting pelvic Group B Acupuncture, once or twice a week until pain intensity (VAS) versus 14% in the control or LBP during delivery or complete recovery (n=37) group (p<0.01) weeks 24-37 A sacroiliac belt, TENS, and physiotherapy were also provided to both groups if needed.
Depledge, RCT Pregnant women 87 Group A (Control) Exercise and advice (n=30) All three groups had significant improvement 2005 with symphysis Group B Exercise, advice and a non rigid pelvic in pain and functional status scores. pubis support belt (Smiley belt) (n=29) No significant differences were found between dysfunction Group C Exercise, advice and a rigid pelvic belt the groups. (Lifecare pubic belt) (n=28)
(Continued)
36 Table 2.2 (Continued) Review of clinical trials related to maternity support belts Study Design Study n Intervention Results population Elden et al. RCT Pregnant women 386 Group A Control (n=130) Group B had significantly less pain than Group 2005 with pelvic Group B Acupuncture 2 days/week for 6 weeks A. girdle pain, (n=125) Group C had significantly less pain than Group between week Group C Individualized stabilizing exercises 6 hours A. 12-31 over 6 weeks period (n=131) Group B had significantly less pain than Group C. Standard treatment (education, pelvic belt (Puff Igang AB, Sweden) and home exercise program) was given to all 3 groups.
Nilsson- RCT Pregnant women 118 Group A Control (n=40) No significant difference in the pain (VAS) Wilmar et with pelvic Group B Home exercise program (n=41) and activity ability at week 38 and 3 months al. 2005 girdle pain, Group C Clinic exercise program (n=37) postpartum. between week 2- 30 Information and a non-elastic sacroiliac belt (Rehband®, Stockholm, Sweden) given to all 3 groups.
Haugland, RCT Pregnant women 560 Group A Control (No treatment was offered) No significant differences in the mean pain 2006 with pelvic pain, (n=285) (VAS) between the groups between week 18 Group B Information, ergonomic exercises, pelvic and 32 of belt/ crutches (n=275) gestation
37 More research is necessary to investigate the use of maternity support garments independent of other therapies before definite conclusions can be drawn about its preventive and therapeutic effects. The experimental periods and the compliance of the belt treatment were not mentioned in most of these studies. One of the essential issues to tackle in future trials is to focus on adequate compliance. Future research should also compare the influence of the different types of maternity support garments and determine whether there are important differences in effect between elastic and rigid supports garments.
2.11 Physiological and psychological changes during pregnancy
A recent garment design study suggested that attention must be paid to the wearers’ bodily changes when designing ergonomic garments (Civitci, 2004). Pregnancy places a woman’s body in a continual physiological and psychological adaptive state (Colman & Colman, 1990). It was therefore anticipated that the physiological and psychological changes during pregnancy would have an effect on women’s clothing preferences and wearing behaviors.
2.11.1 Weight gain and abdominal enlargement
Throughout pregnancy, the uterus enlarges dramatically to accommodate the fetus. At the end of pregnancy, its muscle fibers have lengthened more than 100 times to support the fetus, placenta, and amniotic fluid that weigh approximately 1kg (Cherry & Moss, 2004; Leifer, 2005). While the growing fetus accounts for the majority of weight gain during pregnancy, there is a general increase of 1.4kg of body fluid (Cherry & Moss, 2004). Statistics show that normally two thirds of women during pregnancy gain 6kg to 16kg. The average weight gain is 11.1kg with 1.1kg, 4.9kg, and 5.1kg in the 1st, 2nd, and 3rd trimesters respectively.
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2.11.2 Skin
Women may become more sensitive to touch and may experience excessive perspiration especially after the 3rd month of gestation (Cherry & Moss, 2004; Leifer, 2005). There is an increase of blood flow to the skin as much as 70% by 36th week of gestation (Leifer, 2005). Peripheral vasodilatation and increased sweat gland activity help to dissipate the excess heat to regulate the core temperature of pregnant women. The blood volume increases by 30% to 50%, which begins in approximately the 10th week of gestation and peaks at the 34th week. This is essential to meet circulatory and nutritional demands of maternal and fetal growth (Leifer, 2005). As a result, women may experience heat intolerance or develop irritating skin condition such as heat rash (Cherry & Moss, 2004).
2.11.3 Postural alteration and decreased mobility
The major musculoskeletal changes during pregnancy are postural adjustment and relaxation of the pelvic joints and vertebral joints due to the relaxin hormone. These changes contribute to backache in pregnant women. Several studies have reported different physical changes during pregnancy and its effect on task performance. Gilleard et al. (2002a) found that as pregnancy progressed, forward flexion, axial rotation, motion of the thoracolumbar spine were significantly reduced due to increased body mass and dimensions. Nicholls and Grieve (1992) interviewed 200 pregnant women and revealed that getting dressed and undressed as well as using the toilet were affected by reduced mobility and fatigue, and that forward bending was difficult to perform in connection to the problems of mobility, discomfort, and instability.
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2.11.4 Body image
Significant changes in body weight and shape during pregnancy can affect women’s attitudes towards their body. Studies have shown that some women’s attitudes towards their bodies become progressively more negative during pregnancy (DiPietro et al., 2003; Kamysheva et al., 2008). Given the considerable changes in both physiological and psychological aspects, careful design of medical function garment for women during pregnancy will require accurate identification of their needs, concerns, and problems in the use of maternity support garments.
In the following sections, we will present the current use and health claims of maternity support garments. First, we briefly describe the types and fabrications of maternity support garments. Next, we examine the mechanistic action and design criteria of maternity support garments. Then, we highlight the garment-related problems in terms of comfort, health, aesthetics, and compliance.
2.12 Current use of maternity support garments
Maternity support garments are commercially-available and cost in the range of US $20-$150 (Carr, 2003; Ho et al., 2006; Yip & Yu, 2006). Although not scientifically substantiated, a large number of manufacturers have suggested the health benefits of various types of maternity support garments (Ho et al., 2007). These benefits include the reduction of fatigue, pressure, stress and strain of the back, the prevention and/or the relief of back pain, and the correction of posture.
2.12.1 Types of maternity support garments
Maternity support garment refers to a kind of undergarment that is designed to alleviate pain in the lumbar back and/or pelvic regions during gestation or
40 postnatal period. They can be categorized into four main types: belts, briefs, cradles and torso supports (Ho et al., 2006; Yip & Yu, 2006) (Figure 2.13).
a. Belt b. Brief c. Cradle d. Torso support
Figure 2.13 Types of maternity support garments
A belt (Figure 2.13a), also called a brace, is a long wide band being worn under the abdomen and around the waist. It holds and lifts up the abdomen and exerts pressure at the back. Sometimes it is designed to cross over the lower back and extend to the front side waist and fastened by a Velcro tape. A brief (Figure 2.13b), also called panty, refers to a garment covering the wearer’s abdomen and hip with waist and leg openings. A brief usually has a front panel to encircle the lower portion of the abdomen for supportive function. The extensions of the abdominal panel are either non-adjustable or secured by adjustable Velcro tapes at the sides of the upper hip.
A cradle (Figure 2.13c) consists of only straps and bands worn over the shoulders and across the torso. A torso support (Figure 2.13d) is a vest-like garment that covers the upper torso with a belly-panel of soft extensible fabric and a rigid abdominal support panel at the lower waist.
2.12.2 Fabrications of maternity support garments
41 Today’s commercial maternity support garments commonly use nylon, polyester, spandex, rayon and acrylic, and often blended with cotton. Cotton blended fabric was preferred because natural fiber helps moisture absorption while synthetic fiber usually has surface finishing to promote evaporation of warm vapor and heat transmission (Hollen et al., 1993; Ricci et al., 2006).
The front bodice usually consists of a fabric that was stretchable in the horizontal direction but less stretchy in the vertical direction (Klausen, 1983; Moyer, 1988; Turner, 1992; Walker, 1996). The bottom front panel is usually made from padded material for cushioning and support. The shoulder straps are made from inelastic or semi-elastic fabric, and sometimes with spongy pads. The fabric grain should be carefully considered because the degree of weight support and stabilization of the garment is largely influenced by the force direction and provided by the fabric materials. Maternity support garments are usually fastened by velcro tapes (Figure 2.14a), and less frequently by button and snap fasteners (Figure 2.14b), sliding buckles (Figure 2.14c), hook and loop fasteners (Figure 2.14d), and metal/plastic clasps (Figure 2.14e).
Among the four types of maternity support garments, the belts are most common as there are plenty of patents for the belt designs (Ho et al., 2006). The maternity support belts are also known as pelvic/sacral/sacroiliac/trochanteric supports or belts, binders or braces (Carr, 2003; Heckman & Sassard, 1994; Perkins et al., 1998; Ritchie, 2003). Maternity support belts of different styles and materials (non-elastic, semi- elastic, elastic) are commonly used in studies for the treatment of PLBP and/or PPP (Carr, 2003; Elden et al., 2005; Nilsson-Wikmar et al., 2005).
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Types of fasteners Source of references a Maddux (1985)
b Chin (1993)
c Moyer (1988)
d Wimmer (1989)
e Chin (1993)
Figure 2.14 Types of fasteners designed for maternity support garments
Yu and Wong (2001) interviewed three pregnant women and two medical professionals in a focus group to examine garments’ acceptability using 30 pictures of maternity support garments including nine belts, eight briefs, eight cradles and five bodysuits. They found that maternity support belts were most favored because they were easy to wear, adjust and remove, and they allowed a wider range of fit for the increasing abdominal girth (Yu & Wong, 2001).
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2.13 Mechanical/biomechanical effect of maternity support belts
As previously reviewed, PLBP originates in the lumbar spine region and is a different syndrome from PPP in which pain is predominantly experienced near the sacroiliac joints, in conjunction with or separately in the symphysis. Thus, different mechanistic actions are required in the maternity support belts to achieve the pain relieving effect for PLBP and PPP. One putative mechanism of action of maternity support belts has been proposed. The hypothesis is that the use of a support belt may improve lumbopelvic stability. The support may either press the articular surfaces of sacroiliac joint (SIJ) together, and/or it may place the SIJ in an extreme position to provide stability of the joint (Richardson et al., 2002; Snijders et al., 1976; Snijders et al., 1993; Vleeming et al., 1992).
The maternity support belt is also thought to have a stabilization effect as it may stimulate the actions of different local stabilizers (Mens et al., 2001). For instance, a support belt worn in a high position may simulate the action of the transversus abdominis by the anterior compression on the anterior superior iliac spines and the action of the multifidus by the posterior compression on the posterior superior iliac spines. In a low position, it may simulate the action of pelvic floor muscles. Recent studies showed that lumbopelvic stability is achieved through specific training of the transverses abdomininis, multifidus, and pelvic floor muscles (Hodges, 1999; O'Sullivan et al., 2002; Richardson et al., 2002; Sapsford et al., 2001).
Several studies have reported desirable functions of maternity support belts. Vleeming et al. (1992) investigated the influence of pelvic belts on the stability of the sacroiliac joint in six cadavers. The pelvic belt was found to cause a significant decrease in the sagittal rotation in the sacroiliac joints. The application of a pelvic belt with two different tensions (50 and 100 Newtons) did not differ in the effect on joint rotation. Damen et al. (2002) evaluated the effect of different positions and tensions of a pelvic belt on sacroiliac joint laxity in 10 healthy women. Sacroiliac joint laxity was
44 assessed with Doppler imaging of vibrations. The SIJ laxity was significantly reduced when the belt was worn in a high position (just below the anterior superior iliac spines) rather than in a low position at the level of the symphysis), independent of the tension applied (50 Newton and 100 Newton).
In a similar vein, Mens et al. (2006) assessed 25 subjects with pregnancy- related pelvic girdle pain in the prone position with and without a pelvic belt. The belt was applied in both high and low positions. Sacroiliac joint laxity was significantly decreased in both belt applications compared to the no belt condition and that the belt application in the high position decreased the sacroiliac joint laxity to a significantly greater degree than in the low position. Studies have focused on the mechanical action of maternity support belt on pelvic structures and none of the studies have investigated the possible biomechanical effect of the other three types of maternity support garments on lumbar structures and spinal loading as it uplifts the lower abdomen and redirects the fetal weight to other parts of the body. Thus, the potential beneficial effects of maternity support garments have not been fully maximized and deserve further investigation.
2.14 Design criteria or standards
A maternity support garment is a kind of functional garment. A functional garment is defined as clothing that has a special feature or specific utility for a particular population in health or environmental risk (Lamb & Kallal, 1992). No information relating to therapeutic garment appeared to be available. A literature search was performed to identify published research articles on the design criteria of therapeutic functional garment. The search was carried out on the following databases using the OVID search engine: MEDLINE (1950 to August week 3, 2008), CINAHL (1982 to August week 5, 2008), and Science Direct (1950 to present). The keywords used were ‘design criteria’, ‘design standard’, ‘garment’ and ‘clothing’. The literature search yielded studies limited to the protective and patient clothing (Adams
45 et al., 1994; Gambichler et al., 2006; Wong, 2001), and that none of the studies were related to the therapeutic functional garments.
2.15 Comfort issues in maternity support garments
Carr (2003) examined the Loving Comfort Back Support belt (CMO, Inc., Barberton, OH) among 30 pregnant women and found several garment- related problems of discomfort. They included skin irritation from the seams and the Velcro fastener, discomfort from rolled up and buckled back panel during sitting, and unsatisfactory adjustability, fitting for back support and the noise of Velcro tape.
Yu and Wong (2001) revealed that comfort, support, ease of movement and aesthetics mostly affected the instant preference of a maternity support garment, where comfort was related to the soft and warm hand feel of the fabric as well as adjustable fastening to allow flexibility to accommodate the enlarging uterus; support referred to a corrected posture while standing and walking; ease of movement accounted for how easy to put on and take off the garment was to allow for frequent toileting (2001). Chan (2000) identified comfort, softness, absorbency, function, style, quality, and price as the most important considerations of pregnant women when purchasing maternity clothing.
Wear comfort is multidimensional comprising of all the comfort sensations produced by the garment. It includes thermophyisological comfort, sensory/tactile comfort, comfort during movement, and psychological comfort (Fourne, 1999; Saville, 1999). Thermophysiological comfort concerns the heat and moisture transferability of garment and the way that helps to maintain the heat balance of the body (Fourne, 1999). The wearer feels thermophysiologically comfort when the heat generated by the wearer is in equilibrium with the bodily heat transported through the garment into the environment. The fiber and fabric properties with high moisture vapor permeability contribute to thermophysiological comfort.
46 Sensory/tactile wear comfort concerns the mechanical softness and its lack of prickle and irritation. This comfort relates to the subjective feelings that arise from skin contact with fabrics such as skin irritation, scratching and itching (Saville, 1999). Comfort during movement/dexterity means the ease in movement when wearing the garment. Garment which is cut too small or has too little stretch is considered uncomfortable during movement (Fourne, 1999). Too rigid and non-breathable garment tends to leave a mark over the skin, is more restrictive to movements, and hence less comfortable to the wearer. Psychological comfort concerns the appearance of ‘looking good’ and usability of clothing. The wearer feels psychological comfortable if the garment has the right cut, is fashionable, and matches the social and functional status (Fourne, 1999). All these attributes are influenced by the cut pattern, garment assembly, fasteners, fabric rigidity and stretch ability (Bartels, 2006; Li & Wong, 2006).
The science of clothing comfort has been substantially studied based on fabrics’ mechanical properties (Fan et al., 2002; Li, 2000; Li & Zhu, 2003) and the hand feel of fabrics (Adams et al., 1994; Barker, 2002; Kawabata, 1980; Kawabata, 2002; Li et al., 1998) in specific clothing environments. However, the examination of perceived comfort responses of the interface between the body and clothing in well designed wear trials is lacking.
Maternity support garments are worn next to the skin so there is a close interaction between garment properties and the human body, which are likely to cause different physical effects. Wear trial was demonstrated to be an effective method in clothing research to identify the underlying physical causes of discomfort and to evaluate clothing performance. It simulates the conditions similar to those experienced in ‘normal’ wear (Saville, 1999). However, the comfort parameters being used in Yu and Wong’s study (2001) were not comprehensive and specific enough to reflect the wear comfort within the complete context of human comfort responses, the actual needs of the wearers, and the garment features that contributed to the comfort value.
47 2.16 Health issues in maternity support garments
Mens et al. (1996) reported that some patients using a pelvic belt have experienced an increase in pain within the first 15 minutes of application and it was suggested that the belt should be removed in such circumstances (Mens et al., 1996). Beaty et al. (1999) assessed the effect of the Mother- To-Be maternity support belt (CMO, Inc., Barberton, OH) on the maternal and fetal hemodynamic in 25 pregnant women while wearing it for 20 minutes. No significant changes were found in the maternal blood pressure and cardiac outputs, fetal heart rate (FHR) baseline or variability. It was reported that there were a few isolated FHR decelerations and concluded that the cardiovascular changes were not attributable to the support. However, the use of short experimental periods limit the application of the results since maternity support garments are usually worn throughout the day over a period of several weeks. There is still a need for research to investigate whether long term use would have any adverse effect to the maternal and fetal health. Evidence shows that wearing tight fitting clothing such as girdles and underwear can affect the wearers’ normal physiological balance. Factors affected include dietary carbohydrate absorption (Sone et al., 2000), digestive response (Okura et al., 2000), rectal temperature (Lee et al., 2000), urinary stress hormones (Lee et al., 2000; Sugimoto, 1991), blood pressure (Harumi et al., 2001), and menstrual cycle (Kikifuji & Tokura, 2002).
2.17 Aesthetics issues in maternity support garments
Yu and Wong (2001) found that the cradle design was the most disliked because of the odd and medical appearance which makes it less attractive to wear (2001). Studies examining other garment therapy showed that poor appearance or construction of garment makes the wearers feel unhappy, distressed, embarrassed and self-conscious, which may also lead to poor adherence to the treatment (Johnson et al., 2004; Macintyre et al., 1999). For example, the standard beige color (pressure garments) was reported to have negative connotations of illness/disability (Macintyre et al., 1999).
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2.18 Compliance issues in garment therapy
Different functional garments have been used as a therapy to prevent or treat various medical conditions such as burns and scoliosis (Carr, 2003; Gambichler et al., 2006; Hensleigh, 2002; Kligman et al., 2004; Lee et al., 2005; Macintyre & Baird, 2006; Matthews & Crawford, 2006; Myers et al., 1995). Garment treatment often requires adherence to wearing behavior which largely impacts the treatment effect (O'Hare, 1997). Although compliance rate with garment therapy was often unsatisfactory (Johnson et al., 1994; Lennard, 2003; Stewart et al., 2000), few studies have investigated the factors that may play a role in enhancing the adherence to garment wearing (Carr, 2003; Johnson et al., 1994). Research into medical functional clothing relating to patients’ satisfaction and compliance was mainly focused on pressure garments for burns patients (Brown, 2001; Johnson et al., 1994; Macintyre & Baird, 2006; Ng, 1989; Stewart et al., 2000; Williams et al., 1998), lymphedema (Kligman et al., 2004), varicose veins (O'Hare, 1997); and hemorrhage (Hensleigh, 2002; Tsu et al., 2004) or protective clothing for skin cancer (Gambichler et al., 2006), hip fractures (Myers et al., 1995), and incontinence (Clarke-O'Neill et al., 2007). However, compliance issues in maternity support garments have received little attention.
Williams et al. (1998) found that comfort, color, ease of movement, and donning were the factors of overall satisfaction with the pressure garments for burns patients. Johnson et al. (1994) also reported that the perceived body temperature in the garment, activity limitations, and garment discomfort are the significantly associated with compliance of pressure garments. Myers et al. (1995) found that the elderly patients in using hip protective garments were most concerned about the effectiveness, fit, comfort, laundering, cost, not ‘showing’, and ‘looks well’. O’Hare et al. (1997) reported that comfort and fit promoted the compliance with compression garments for venous disorders. Like other garment therapy, it
49 is anticipated that maternity support garments would have similar garment- related factors that affected the wearing compliance.
In view of the lack of scientific research and basis in the existing garment designs, and limited knowledge in the comfort, health, aesthetics, and compliance issues in maternity garment therapy, an exploratory approach is appropriate in gathering data to support future research. Therefore, in this study, the wear trial and interviews were planned with sound methodologies and techniques to explore the pregnant women’s needs and preferences in maternity support garments in relation to the designs and fabrications, which will be explained in the Chapters 4 and 5.
In order to develop a functional garment that is effective, safe, comfortable and aesthetic to wear, scientific research should be carefully designed and developed with a systematic approach together with the application of current knowledge in ergonomics, human biology and psychology, and human interactions with garments. Next, we will review the physiological and psychological changes during pregnancy, recent literature on the physiological effects of intimate apparel, and the design frameworks used in product development.
2.19 Physiological effects of intimate apparel
A recent review by Ho et al. (2005) demonstrated that poor-vapor- permeability fabric can lead to elevated temperature, humidity and pH in the microenvironment between the skin and the garment, which can cause skin reactions and skin infections such as the occurrence of Candida infection and dermatitis (Ho et al., 2005). The review also showed that experimental studies on intimate apparel such as girdles and underwear have indicated that the pressure exerted by clothing adversely affected certain aspects of the normal physiological balance of the wearer’s body (Ho et al., 2005). Factors affected included dietary carbohydrate absorption, digestive response, rectal temperature, urinary stress hormones, blood pressure, and nervous system.
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2.20 Design frameworks
In the overall product life cycle, prior to the product manufacturing and distribution, product development is a crucial phase whereby many new ideas and choices integrate to form one product. Numerous different frameworks for product development and design have been extensively researched (Carroll, 2001). Carroll (2001) summarized many of these frameworks as presented in Table 2.3 and concluded that each framework comprises specific steps which can be placed within one of the four broader categories: a). generating design ideas, b). sketching and constructing first garment, c). evaluating feasibility and planning production, and d). implementing plans and re-evaluating where necessary (Carroll, 2001).
Among these frameworks, DeJonge’s functional design process is generally accepted by clothing and textile researchers to be a landmark with which clothing designers develop their own design processes. It has also been used to guide research into the development of garment design criteria and prototype. Examples of previous research that have used the full, or adaptations of, DeJonge’s basic design framework are clothing for women with physical disabilities (Carroll, 2001), intimate apparel designs for women (Chan, 2001) and hospital clothing for neonates (Bergen et al., 1996). For the above reasons, this study was conducted to design and develop a new product of maternity support garment based on DeJonge’s design framework. Details of the design process based on DeJonge’s framework are presented in Chapter 6.
Current scientific knowledge and systematic design framework are necessary to guide scientific investigation of design and development of maternity support garments. While there is a large body of anecdotal evidence from the manufacturers that supports their use, limited evidence is available on the effectiveness of maternity support garments in the treatment of PLBP and/or PPP.
51
) . 50 p
, 2001 , from Carroll from ( literature literature g n frameworks from clothin n frameworks g ment and desi p roduct develo p g Existin Table 2.3
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2.21 Summary and conclusions of literature review
It is clear that PLBP and PPP are significant and costly health problems. The maternity support belt is widely advocated by healthcare professionals and lay persons to manage the pain symptoms as it is an easily-accessible commercial product. Although there is a great wealth of anecdotal evidence on the health effects, no research evidence was found in the design criteria of these garments. Secondly, the problems related to the garment features have raised a concern for comfort, treatment compliance and health effect. Thirdly, convincing evidence of effects of belt wearing on PLBP and PPP is still lacking. Lastly, the objective measurements needed to evaluate the underlying mechanisms of maternity support garments have not been established.
Thus, the main focus of this study was to determine scientific design criteria for developing a maternity support garment and to investigate the effectiveness of this maternity support garment on PBLP in terms of subjective pain assessment and objective biomechanical measures. The reasons for studying PLBP are as follows. PLBP is distinctly different from PPP which requires being clearly defined and different treatment, and individual research investigation. Furthermore, even though PLBP often recurs and becomes chronic, and LBP after delivery accounts for high economic costs among the general population in a long term basis, most studies have been performed to investigate PPP and PLBP, or PPP alone. Little research has investigated on PLBP. The objectives and design of this study will be discussed in the next few chapters.
Some of the literature from this chapter has been presented in International Fiber Societies Conference, Seoul (30 May – 2 June) and published in Innovation and Technology of Women's Intimate Apparel. Cambridge: Woodhead Publishing Limited, p.132-150.
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CHAPTER 3
THE RELATIONSHIPS AMONG BIOMECHANICAL MEASURES DURING PREGNANCY: A LONGITUDINAL STUDY
3.1 Introduction
This chapter describes the biomechanical study in the exploratory phase. We examined the trends, the differences and relationships among 6 biomechanical measures in 29 pregnant women at weeks 12, 25 and 36 of gestation. The measures include the centre of pressure during natural stance (COPN), centre of pressure with lumbar reference (COPL), sagittal lumbar curvature (SLC), body weight (BW), body mass index (BMI), and sagittal abdominal diameter (SAD). The COP locations were measured by a force platform and the SLC was measured by a sliding gauge. The details of the methods, procedures, and instruments used to determine the biomechanical measures will be presented in the following section. The results and implications of the study will be discussed with reference to existing literature.
3.2 Methods
3.2.1 Study population
The university ethics committee and the Institutional Review Board of the hospital approved the experimental protocol. Written informed consent was sought from all subjects. This longitudinal study involved completing a demographic questionnaire (Appendix 11) and having biomechanical measures taken at weeks 12, 25 and 36 of gestation. 48 pregnant Chinese women who were attending routine antenatal check-up at a local university hospital were recruited by convenience sampling. Inclusion criteria are
54 women with a singleton pregnancy. Subjects who had previous spinal surgery, structural damage or gross structural defect of the spine or a known history of musculoskeletal disease were excluded. Those with a known history of LBP that lasts for 12 weeks duration or more, or LBP due to specific underlying pathology such as infection, tumor, osteoporosis, rheumatoid arthritis, fracture, or inflammation were also excluded to eliminate any postural adjustments due to LBP rather than pregnancy.
3.2.2 Pain assessment
Lumbar back pain was assessed by a Numeric Rating Scale (NRS); with 0 representing no pain and 10 representing the worst pain imaginable (Appendix 13). The subject is asked to state the single number that best represents the level of pain intensity. The functional status affected by lumbar back pain was assessed by the Roland-Morris Disability Questionnaire (RMDQ) (Appendix 15). It contains 24 yes/no items. The subject was asked whether the statements apply to them that day (i.e. the last 24 hours). The RMDQ-24 score is calculated by adding up the number of “yes” items, ranging from 0 (no disability) to 24 (maximum disability). The NRS and RMDQ are valid and reliable instruments to evaluate pain intensity (Grotle et al., 2005; Ostelo et al., 2005) and functional status
(Grotle et al., 2004; Roland & Morris, 1983) in low back pain patients.
3.2.3 Biomechanical measures
3.2.3.1 Body weight (BW) and body mass index (BMI)
Body weight was measured to the nearest 0.1 kilogram (kg) on a calibrated balance beam scale (Detecto, Inc, Webb City, Mo.). BMI was calculated as weight (kg) divided by height in metres2 (m2).
55
3.2.3.2 Sagittal abdominal diameter (SAD)
The sagittal abdominal diameter (SAD) in unit centimeter (cm) was measured using a Martin large sliding caliper (Yamakoshi Senisakusho Co. Ltd., Tokyo, Japan) and recorded to the nearest 0.1 cm. The SAD is the anteroposterior diameter of the abdomen in the sagittal plane during standing, which is the distance from the back to the upper abdomen; midway between the top of the pelvis and the bottom of the ribs.
3.2.3.3 Sagittal lumbar curvature (SLC)
The sagittal lumbar curvature (SLC) in unit degree during natural upright stance was measured by a sliding gauge (Yamakoshi Senisakusho Co. Ltd., Tokyo, Japan) (Figure 3.1a). The tangential lines were drawn along the spine contour of the lumbar region. The maximum angle between two tangential lines at the end of the lumbar region was defined as the sagittal lumbar curvature presented by an angle θ (Figure 3.1b).
Figure 3.1 (a) Spinal gauge for the measurement of sagittal lumbar curvature (b) Sagittal lumbar curvature defined by angle θ
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3.2.3.4 Centre of pressure during natural stance (COPN)
The location of the centre of pressure in unit millimeter (mm) was measured by a force platform (Jockey Club Rehabilitation Engineering Centre, PolyU, HK) (Figure 3.2a). Four strain gauge type load cells are located at the corners under the platform. The signals of the load cells were digitized using an analogue-to-digital (A/D) converter with sampling rate of 600 Hertz and recorded in a computer via system interface (Figure 3.2c). The platform was demonstrated to be a highly valid and reliable tool with an intraclass correlation coefficient (ICC) of 1.00.
The subjects were asked to wear a hospital gown during the data collection. To obtain COPN, the COP measurement was performed three times in a natural upright stance posture during each of the three visits. The mean of three trials was used for data analysis.
The subjects were asked to step down from the platform and allowed a brief rest in between consecutive COP measurements. Each kinetic measurement lasted for approximately 10 seconds. During the measurement, each subject was asked to relax and stand upright on the platform without leaning on any object (Figure 3.2b). Both arms hung freely on the sides of the body. The head was in its natural position with eyes focusing on an eye level object affixed on the opposite wall at an approximate distance of 100 cm. The subjects stood with bare feet and were allowed to stand with the feet apart at a self-selected comfortable distance. All subjects were asked to stand next to a feet bar without leaning on it. Thus, the location of the COP in the anterior-posterior direction was measured relative to the heels where they were in contact with the feet bar.
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3.2.3.5 Centre of pressure with lumbar reference (COPL)
When the subject became comfortable in her natural standing posture, a short aluminum probe was extended from the platform to rest gently over the subject’s lumbar spine at the level of L3 (Figure 3.2b). This probe extension distance was recorded and applied to the same subject for COP measurements with lumbar reference (COPL) in the subsequent visits. The subject was asked to remain in the same position with the probe touching her back but which was not leaned on. The consistency of the COP measurements over the 3 trials during each visit was established with ICC. The test-retest reliability of the COP measurements was moderate to high (ICC = 0.58 to 0.81).
Figure 3.2 (a) The centre of pressure platform with four load cells (LC) located at the corners. (b) The position assumed during centre of pressure measurements with both heels lightly touching the feet bar (FB); the aluminium probe (AP) was extended for centre of pressure with lumbar reference only; the handrail (HR) is a means of support for ascension and descension between each measurement. (c) The schematic diagram of the centre of pressure measuring system. 58
3.2.4 Data Analysis
All analyses were performed using SPSS for Windows version 14.0 (SPSS Inc., Chicago, IL) with level of significance set at 0.05. Descriptive statistics were used to analyze the demographic, clinical and biomechanical data. Repeated measures ANOVA were used to examine the differences in the biomechanical measures among the three visits. Pearson correlation coefficients were performed to investigate the relationships among the magnitude and changes of biomechanical measures. Continuous variables with missing data were replaced by the mean score of all other subjects for that particular variable (Portney & Watkins, 2000a).
3.3 Results
3.3.1 Demographics
Nineteen subjects were excluded due to incomplete data because they were too tired or had no time (6), were followed up with other clinics (5), were unable to contact (6), had twins (1) and had miscarriage (1). The final sample therefore consisted of 29 subjects. The demographic and clinical characteristics of the subjects are presented in Table 3.1.
3.3.2 Pain intensity
Table 3.2 shows the clinical presentation of PLBP in the pregnant women of this study from the first trimester to the third trimester of gestation. 83% of the women reported to have PLBP one or several times during the assessment period with the most occurrences in the second trimester (58.6%). As pregnancy progressed, more women experienced PLBP compared to early pregnancy. The Roland-Morris Disability Questionnaire showed that the pain usually affected daily activities such as standing, walking, sleeping, and getting dressed.
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Table 3.1 Demographic and clinical characteristics of the subjects (n=29) Characteristic Mean (SD) or number (%) Age (years) 34.2 (4.5) Body weight (kg) (before pregnancy) 52.6 (7.4) Body height (cm) 157.5 (4.8) Body Mass Index (kg/m2) 21.2 (3.3) Full time work (%) 21 (72.4) Primiparas (%) 18 (62.1) Gestation weeks at follow up First trimester (weeks) 12.0 (1.6) Second trimester (weeks) 25.2 (1.9) Third trimester (weeks) 35.6 (1.2) LBP during previous pregnancy (%) 4 (13.8)
Table 3.2 Clinical presentation of the subjects who experienced PLBP First Second Third trimester trimester trimester PLBP experience (%) 31.0 58.6 46.7 NRS - Average (0-10) 4 (1.5) 3 (1.9) 4 (1.6) NRS - Peak (0-10) 4 (1.5) 3 (2.4) 5 (2.1) RMDQ score (0-24) 7 (5.0) 5 (5.2) 6 (3.5) NRS = Numeric Rating Scale, RMDQ = Roland-Morris Disability Questionnaire *The above data only include the subjects who reported PLBP during this pregnancy.
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3.3.3 Biomechanical measures
Table 3.3 summarizes the significance levels of change of various biomechanical measures during pregnancy using repeated measures ANOVA. As expected, as pregnancy progressed, there was a significant linear increasing trend in the body weight, body mass index, sagittal abdominal diameter, and centre of pressure with lumbar reference. When compared to the first trimester, the weight gain of the subjects was 8.9% and 8.5% between each trimester and the sagittal abdominal diameter was increased by 19.5% and 19.0% between each trimester (Table 3.3).
Table 3.3 Significance level of changes of various biomechanical measures with time using one-way repeated measures ANOVA (n = 29) First Second Third F P value trimester trimester trimester (Week 12) (Week 25) (Week 36) BW (kg) 55.1 (6.9) 60.0 (7.5)† 64.7 (8.0)‡ 132.605 0.000** BMI (kg/m2) 22.3 (3.1) 24.1 (3.2)† 26.1 (3.3)‡ 139.965 0.000**
COPN (mm) 37.5 (11.0) 31.9 (9.0) 32.4 (10.0) 14.661 0.001** (T1 & T2)
0.000** (T1 & T3) COPL (mm) 21.5 (10.4) 27.3 (10.2) 33.8 (11.7) 52.0 0.000** SLC (0) 40.2 (8.6) 39.6 (6.7) 39.6 (7.8) 0.221 0.737 SAD (cm) 22.0 (2.6) 26.3 (2.0) 30.5 (1.9)§ 390.786 0.000** Additional 3.9 9.6 moments (Nm) Number of Missing data: § = 1, † = 2, ‡ = 3 Data are presented as mean (SD) unless stated otherwise. **P<0.01, *P<0.05 BW = Body weight, BMI = Body mass index, COPN = Centre of pressure during natural stance, COPL = Centre of pressure with lumbar reference SLC = Sagittal lumbar curvature, SAD = Sagittal abdominal diameter, T1 = First trimester, T2 = Second trimester, T3 = Third trimester
61 Figure 3.3 shows a free body diagram with all the resultant external forces acting on a pregnant woman in static equilibrium. In general, when taking moments about L5, the moment of the trunk muscles is calculated by the equation as shown below:
MMg٠a + MFg٠b = FM٠c where a, b and c are the distances of the moment arms
Figure 3.3 External forces acting on a pregnant woman
62 To calculate the additional flexion moments in the second and third th trimesters, the centre of mass (Li) of the expectant mother in the i trimester
(Ti) was assumed to lie halfway along the distance of the sagittal abdominal depth anterior to the spine centre (Figure 3.4). The weight gain during pregnancy was assumed to involve solely the upper part of the body. The moments (Mi) imposed on the spine at the L5-S1 level was calculated in
Newton meter (Nm) by multiplying the body weight gain (Wi) by the
estimated centre of mass (Li). Thus, the equation for determining the additional flexion moments is as shown below:
Mi = Wi x (Li + L1)
where L1 was calculated by subtracting the distance (d) between the spine centre and the back surface from the sagittal abdominal depth (A) in the first trimester. The distance (d) is estimated to be 10cm since the distance between the centre of back extensor muscle and the lumbar disc centre is assumed to be 5cm (McGill & Norman, 1987).
Figure 3.4 Estimated centre of mass to determine additional flexion moments
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3.3.4 Correlation among the biomechanical parameters
As shown in Figure 3.5, the mean SAD and BMI were significantly correlated in all three trimesters as pregnancy progressed from the first (r2 = 0.76, p<0.001), second (r2 = 0.53 p<0.001) and third trimester (r2 = 0.30, p<0.01). As pregnancy progressed, similar significant correlations were shown between the mean SAD and BW in the three trimesters from the first (r2 = 0.64, p<0.001), second (r2 = 0.49, p<0.001) to third (r2 = 0.19, p<0.05) trimesters.
35
T1
T2
T3 30 ) 2
25 BMI (kg/m BMI
20
15 15 20 25 30 35 SAD (cm)
Figure 3.5 Relationship between the means of sagittal abdominal depth and body mass index during the three trimesters (n = 29)
64 Significant correlations were found between the changes in COPL and SAD from the first to the second trimester (r2 = 0.23, p<0.01) and from the first to the third trimester (r2 = 0.22, p<0.05). The mean COPL and BW have a weak correlation from the first to the second trimester (r2 = 0.16, p<0.05). However no correlation was found among COPN, BW, BMI, SAD and the estimated moment.
For the COP during natural upright stance, in response to the linear increase in COPL, there was a significant difference only between the first trimester and the second trimester (Figure 3.6). Examination of these means suggested that the subjects had their COP shifted posteriorly from the first trimester to the second trimester. In support of this, there was a linear trend, F (1, 28) = 25.732, P < 0.001, eta2 = 0.48. However, the finding also showed a significant quadratic trend, F (1, 28) = 7.640, P = 0.01, eta2 = 0.21, reflecting that the COP shifted anteriorly from the second to the third trimester.
40 COPN 38 COPL 36
34
32
30
28
26 Centreof pressure (mm) 24
22
20 First Second Third
Three trimesters of pregnancy
Figure 3.6 Effect of pregnancy on centre of pressure shift and the compensatory response of centre of pressure shift (n = 29)
65 As seen in table 3.3, the COP with lumbar reference shifted more anteriorly as pregnancy progressed. The data shows that in response to the anterior COP displacement with lumbar reference (~6mm) from the first to the second trimester, there was a corresponding posterior COP displacement during natural stance (~6mm). However, from the second to the third trimester, while there was a further anterior displacement in COP with lumbar reference (~7mm). The evidence of the finding shows that the COP displacement during natural standing did not continue to shift posteriorly, but rather more anteriorly (0.5mm). The means of COPN and COPL were significantly correlated in the first, second and third trimesters (r2 = 0.50, p<0.001, r2 = 0.44, p<0.001 and r2 = 0.35, p<0.01) correspondingly (Figure 3.7).
75 T1 y = 0.6651x – 3.4749, r2 = 0.50 2 65 T2 y = 0.7645x + 2.8853, r = 0.4503 T3 y = 0.687x + 11.512, r2 = 0.35
55
45
35 COPL (mm)
25
15
5 5 15253545556575 COPN (mm)
Figure 3.7 Relationship between the means of centre of pressure during natural stance and centre of pressure with lumbar reference during the three trimesters (n = 29)
66 However, no significant trend was observed in the SLC during pregnancy. This suggests that the lumbar curvature was not significantly affected by the increased moments. The changes of SLC were also weakly correlated with the increase in BW (r2 = 0.19, p<0.05) and the increase in BMI (r2 = 0.18, p<0.01) between the first and third trimesters.
3.4 Discussion
While the prevalence of low back pain during pregnancy has been shown to be high, postural alteration has been hypothesized as a major cause (Daly et al., 1991; MacEvilly & Buggy, 1996; Monaco, 1996; Ritchie, 2003). Therapeutic interventions aim to relieve LBP through restoration of the postural alignment. However, no objective measures are available yet to evaluate the biomechanical effects of these treatments on postural realignment. This study examined the trends, the differences, and the relationships among six biomechanical measures that occurred from the first trimester to the third trimester of pregnancy with the aim to identify an objective measure to assess the biomechanical effects.
83% of the women in the study experienced back pain during pregnancy. This finding is consistent with Bullock, Jull & Bullock, (1987) and Franklin et al., (1998) who reported similar incidence of back pain. The mean pain intensity was 3-5 out of 10 on the Numeric Rating Scale (Table 3.2), also similar to previous studies that found back pain during pregnancy was mild to moderate (Kristiansson et al., 1996; Ostgaard et al., 1996).
The finding of significant increases in body weight and sagittal abdominal diameter as pregnancy progressed were consistent with the statistics showing that normally 2/3 of women gain 6kg to 16kg during pregnancy and that the average weight gain is 1.1kg in the first trimester, 4.9kg in the second trimester and 5.1kg in the third trimesters, which adds to an average of 11.1kg. Ostgaard et al. (1993) studied 855 Swedish pregnant women and reported a 22% weight gain from week 12 to week 36 and their sagittal abdominal diameters were increased by 27.7% and 21.7% respectively in
67 week 24 and week 36 In this study, the lesser weight gain and trunk measurements can be explained by the smaller stature in the Asian population compared to the Caucasian.
It is interested to find that there were significant correlations among the anterior shift of COP, the enlarging sagittal abdominal diameter, the increase in body weight and body mass index. It indicates that the effect of pregnancy on the anterior COP displacement can partly be explained by the increased trunk mass and the body weight gain. These findings support the literature that the growing fetus accounts for most of the weight gain during pregnancy (Cherry & Moss, 2004). Kinoshita (1985) reported that during load carrying of 20% body weight, the vertical and anteroposterior ground reaction force, but not mediolateral forces, are magnified in proportion to the added mass of a load.
Literature relating to the causes of low back pain during pregnancy speculated that as the growing gravid uterus shifts the centre of gravity anteriorly, women compensate for postural imbalance by alteration of postures which is one of the contributing factors for pain in the low back and sacroiliac joint (MacEvilly et al., 1996; Ritchie et al., 2003). This study provides evidence in the effect of pregnancy on the more anterior position of the centre of pressure in conjunction with the compensatory responses of the centre of pressure during natural stance and of the sagittal lumbar curve from the first to the third trimester.
The principal finding is that from the first to the second trimester, the magnitude of posterior displacement of COPN (~6mm) was proportional to the magnitude of the anterior displacement of COPL (~6mm). It indicates that the anterior load tends to displace the posture away from the equilibrium (a deviation from the original position) and is counteracted by a comparative contribution of restorative forces to return the posture toward the equilibrium state. In support of this, correlation analysis showed that 35% to 50% of the total variance in the means of COPN could be explained by the means of COPL in all three trimesters. This shows that the anterior
68 COP displacement leading to postural instability was to some extent compensated by the postural adaptation of posterior COP shifting. The finding fits well with the literature relating to the spinal stability and control (Reeves et al., 2007). When the spine and torso are disturbed from the equilibrium, the CNS responds to the postural instability by utilizing some or all of the feedback pathways (reflexive and voluntary muscle activation) of the spine to provide the appropriate force to stabilize the spine and to minimize the risk of injury. Fries et al. (1943) also reported in a case study that there was posterior displacement of centre of gravity during natural stance varying from 5.1% to 17.9% from the first to the third trimester of pregnancy.
As pregnancy advanced from the second to the third trimester, although there was a further anterior COP displacement (~7mm), additional compensatory response during this period was not apparent. It suggests that the body’s equilibrium demands are substantially challenged by alterations in the centre of mass during this time which may lead a loss of stability, as subjectively reported by 200 pregnant women in Nicholls & Grieve’s (1992) study. This indicated that the back muscles have to take up the major role in maintaining postural equilibrium. This would subsequently increase the load on the spine as well as fatigue of the back muscles. Both increased spinal loading and muscle fatigue would increase the risk of injury to the spine. The results provide direct evidence to the theories regarding the causes of LBP during pregnancy. It is suggested that the assessment of centre of pressure during natural stance can provide a useful measure to quantify the biomechanical effect of different interventions on postural alignment and stability. Studies have demonstrated that a real or perceived threat of injury leads to significant changes in trunk muscle recruitment pattern (Hodges et al., 2003; Moseley et al., 2004). Nevertheless, potential injury mechanisms that link instability and LBP may be of interest for further research.
The reasons for reduction in the compensatory response in the sagittal plane from the second to the third trimester are unclear. Previous findings of an increase in step width as pregnancy progressed and increased hip abduction
69 moment in late pregnancy (Bird et al., 1999; Foti et al., 2000) may partly explain the diminished anteroposterior response. It is possible that as pregnancy progressed over a considerable period of time, the ability and the level of trunk and pelvic extensor muscle activation would be decreased as the muscle endurance limit has been reached in connection to the increasing load and muscle fatigue. Static muscular contractions sustained over long periods, even at low levels, can lead to fatigue and the manifestation of pain, but there appears to be a threshold of 5% maximum voluntary action (MVA), below which muscle contraction can be sustained indefinitely (Bjorksten & Jonsson, 1977).
Throughout pregnancy, the postural adaptation utilized to compensate for postural instability did not seem to involve the lumbar strategy because the lumbar curve was unchanged. Previous studies have also reported no significant relationship between back pain experienced in the pregnant women and the magnitude or change in lumbar lordosis (Bullock et al., 1987; Franklin & Conner-Kerr, 1998). It is plausible that pregnant women maintain balance by cervical spine, upper trunk, hip, and ankle strategies. The interpretation is supported by biomechanical studies of pregnant women reporting significant increases in the thoracic kyphosis (Bullock et al., 1987), posterior head position and pelvic sagittal tilt (Franklin & Conner-Kerr, 1998) during standing, and significant increases in hip and ankle kinetic gait parameters (Foti et al., 2000).
One limitation of this study that needs to be addressed is the low test-retest reliability (0.58) for COPN. Caution should be taken to interpret the data. The challenge faced during the data collection was that pregnant women tend to have greater postural sway as pregnancy progressed due to the increased anterior load. Longer trial tests (for example, one minute) should be considered in future studies to examine which period within the minute would be the least fluctuation in COP and adopt the most appropriate measurement strategies.
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3.5 Conclusions
The results showed that the subjects had a linear increase in body weight and in sagittal abdominal diameter between each trimester and that most of the weight gain is due to the increased trunk mass. The effect of pregnancy on the centre of pressure shift was quantified. The effect of increased anterior load and flexion moment to the spine on the lumbar spine curvature was however not observed. The findings showed that the compensation strategy of COP shift in response to the increased trunk mass was apparent between the first and the second trimesters but not between the second and the third trimesters. The latter finding may have implications for potential injury to the spine as the spine system may become unstable because of postural instability. Because of the low test-retest reliability coefficient, the results should be interpreted with caution. The centre of pressure may be useful to assess the biomechanical effect of therapeutic interventions on postural alignment and stability.
Data presented in this chapter has been presented in Evidence-Based Practice in Nursing: Paradigms & Dialogue Conference, Hong Kong (April 19-21) and BMC Musculoskeletal Disorders (1st revision in progress).
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CHAPTER 4
GARMENT NEEDS OF PREGNANT WOMEN BASED ON CONTENT ANALYSIS OF IN-DEPTH INTERVIEWS
4.1 Introduction
This chapter describes the semi-structured interviews in the exploratory phase of the investigation. Interviews are useful for identifying information where little is known and for revealing details that might be overlooked in statistical analysis (Strauss & Corbin, 1990). Interviews were conducted with 10 pregnant Chinese women who experienced low back pain during pregnancy. All the interviews followed a detailed interview guide and 8 different maternity support garments were shown to the participants as a method of tangible objects to stimulate responses. Content analysis was used to analyze the needs, concerns, and problems of pregnant women when using maternity support garments.
4.2 Methods
4.2.1 Qualitative approach
This study used in-depth interview as a qualitative approach which allows the researcher to explore and define the users’ personal views of their ergonomic needs for maternity support garments; and applied content analysis for examining individual participant’s psychological feeling and attitude towards garment treatment during pregnancy. Detailed data of their preferences, decision processes and priorities of maternity support garments were categorized with codes, and organized systematically.
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4.2.2 Study sample
Interviews were conducted at an antenatal clinic of a regional hospital in Hong Kong. The inclusion criteria were women in the third trimester of pregnancy who had experienced low back pain during current pregnancy, and able to communicate fluently in Cantonese. The sample size was determined based on a guiding principle of data saturation, that is sampling to a point at which no new information is obtained and redundancy is achieved (Polit & Beck, 2004). In qualitative research, a sample of 10 good informants who can communicate effectively on their experiences is reasonably adequate for understanding the studied phenomenon (Polit & Beck, 2004).
4.2.3 Data collection procedure
Ethical approval was obtained and participation was on a voluntary basis. Written informed consents were obtained after explanation of the purpose and procedure of the study. Background information of the participants was collected using a questionnaire including demographic and clinical data (Appendix 11). Prior to the main study, a pilot interview was undertaken to check clarity of wordings and logical flow of the questions. The questions were approved by a panel representing different professions, such as nurses and textile experts to improve face validity. Three pregnant women were recruited from the same antenatal clinic for the pilot interview. The respondents in the pilot study found that the questions were easy to understand and were relevant to the topic of interest. No major amendments were made to the questions.
All interviews took place in a private room at an antenatal clinic and were audio-recorded. The interviews began with some general questions about pregnancy as a warming up session to encourage conversation, it then proceeded to discuss the needs for and the use of maternity support garments. This semi-structured interview used an interview guide and
73 showed different garment samples (Figure 4.1) to each participant so as to stimulate answers by means of real objects. The rationales for choosing these 8 maternity support garments are given in next chapter.
4.2.4 Validity and reliability
To ensure that the data collected were reliable and valid, audio-recorded interviews were used effectively to provide complete and accurate participants’ responses. They allowed verbatim transcription which minimized the errors generated from researcher’s recall of memory. In qualitative research, the criterion of validity that are used to establish the trustworthiness of qualitative data is credibility (Whittemore et al., 2001).
Credibility refers to the conscious effort to establish confidence in the truth of the data and accurate interpretations of the meaning of the data (Carboni, 1995; Lincoln & Guba, 1985). To ensure credibility of data in this study, a comfortable, private and neutral setting was provided throughout the interview in order to enhance a free and interactive atmosphere for prolonged engagement; that is essential for building trust and rapport between the participants and the interviewer to ensure an adequate scope of data coverage. The interviewer continuously observed the responses that allow the interaction to focus on the aspects relevant to the phenomenon being studied in order to provide adequate depth of the responses. These techniques were used to ensure the generation of useful, accurate, and abundant information (Polit & Beck, 2004).
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Garment A Garment B 10cm front panel Rectangular Large bowl-shape Pentagon supports lower reinforcement at stretchable panel reinforcement at abdomen centre back covers the whole belly centre back
Garment C Garment D 7.5cm front panel Wide trapezoid Large soft abdominal The 4cm elastic supports lower reinforcement for the panel with 4cm elastic band extends to the abdomen back band at the lower back abdomen
Garment E Garment F Thick wide cushion 7cm wide strap wrap Soft & large oval 7.5cm Sling intersect oval-shape front around back waist shape fleece front at the back and portion portion fasten at front
Garment G Garment H 7.5cm elastic band 3cm elastic strap A vest with 5cm rigid Hexagonal panel at supports the lower over shoulders and fabric panel at lower the back abdomen across torso abdomen
Figure 4.1 Commercially-available maternity support garment samples showing the descriptions and the front (left) and back (right) views worn on a dummy
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4.2.5 Data analysis
Content analysis was used based on a categorization scheme to code and interpret the data (Polit & Beck, 2004). This method is useful for unstructured materials and sensitive to the context. Before content analysis, each audio file of interview dialogue was transcribed into Chinese and then translated into English by the same researcher to ensure consistency and validity (Twinn, 1997). All the dialogue details were carefully reviewed and coded for correspondence to the identified categories, which would be meaningful to the research problems (Strauss, 1998). The process of coding data involved seeking recurring themes in the data representing patterns in different categories and themes.
4.3 Results
The method of showing real objects of different maternity support garments to the participants was useful as it provided tangible samples to stimulate more distinct responses. In particular, subjects tended to touch the garments by hands before commenting on the thermal, moisture and tactile comfort.
A total of 13 pregnant Chinese women were invited to participate in the study by convenience sampling. They all accepted but three of them were not interviewed because of delivery or not showing up. Therefore, the final sample consisted of 10 pregnant Chinese women aged 33.4 (S.D. 2.8) ranging from 29 to 37, either Para 0 or Para 1 (parity refers to the number of previous birth given) who worked full time (60%) or were housewives (40%). Their mean gestational age was 36.1 (S.D. 3.8). The first complaint of back pain occurred at 20th week and reached the peak intensity at the 30th week of pregnancy. The mean intensity of pain was reported 4.0 (S.D. 2.2) and peak pain intensity was 5.7 (S.D. 1.8) on a numeric rating scale from 0 to 10. The clinical presentation of pain onset and intensity was consistent with previous studies (Wu et al., 2004).
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Maternity support garment was made known to all participants that it helps to reduce back pain during pregnancy. Prior to the interview, 90% of the participants had experiences in wearing maternity support belt or brief, the source of information mainly came from their relatives, friends and salespersons in maternity product store. However, only 30% have worn the belt throughout the whole period of pregnancy. The reasons for discontinuation included excessive heat, perceived ineffectiveness, itchiness, excessive pressure around the abdomen, and inconvenience of adjustment.
As seen from above data, the study sample mainly consisted of women who have prior belt wearing experience. Given their familiarity with the belts, they were able to express their views and experience in the context of the real garment samples. There was a potential bias related to the prior negative experience. The women who had a ‘good’ experience might tend to think more positive of the products whereas those who had a ‘bad’ experience might have an opposite view. However, the assessment of the garments did not seem to be influenced by the women’s prior experience since they were able to express both ‘positive’ and ‘negative’ components in the garments.
77 Table 4.1 shows five main themes of needs, concerns and problems expressed by the participants in using maternity support garments.
Table 4.1 Percentage of participants expressed their needs/concerns/problems in using maternity support garment (n = 10) Themes √/× Needs/concerns/problems % of participants Effective function √ Pain relief function 80% √ Supportive function 80% √ Supports abdomen 60% √ Supports back 20% Safety × Baby’s comfort and growth 30% × Risk of fall 20% Skin comfort √ Comfort 90% × Hot and sweating 100% × Itchiness, skin rash or infection 100% × Fabric too thick 80% √ Breathable fabric 90% √ Water absorbent 80% √ Cotton 100% × Polyester or nylon 40% √ Soft and smooth fabric 90% × Pressure (too tight) 80% × Pressure over breasts 10% Continued
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Table 4.1 (Continued) Percentage of participants expressed their needs/concerns/problems in using maternity support garment (n = 10)
Themes √/× Needs/concerns/problems % of participants Aesthetics √ Simple style 70% √ Looks good 80% √ Fashionable or sporty 30% √ Fits body well (nice shape, not 70% bulky) √ Resembles undergarment 40% √ Adjustable feature 70% √ Accessories 30% √ Invisible 60% √ No skin marks 40% √ Color 90% Easy to put on √ Simple and convenient to put 100% and take off on and take off :) Needs = √, concerns or problems = ×
4.3.1 Effective function
80% of the participants felt that it is most important that the maternity support garments are able to relieve back pain during pregnancy. When they were asked to name the possible causes of low back pain, the responses varied. 80% of them said it was related to the increasing fetal weight and altered posture, so they believed that pain relief could be achieved through effective support to the abdomen (60%) and the back (20%). However, 40% of them questioned whether the commercially-available garments would provide the necessary functions.
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If you want to convince me to buy one (a maternity support garment), it is important that it works. Can it (the maternity support garment) really help to lift up the belly and relieve the backache? I think this (the cradle G) is better because the belly is provided an uplifting support by the shoulders. (P8, clerk aged 34)
I hope that it (the maternity support garment) can really support my abdomen well and really relieve my (back) pain after I use it (the maternity support garment)…I think the weight of the baby made my low back pain worse…as my belly suddenly became bigger and heavier, the back needs to provide more supporting force to compensate for the weight... (P3, housewife aged 30)
It (the back panel) gives support to my back. Also, the Velcro at the bottom part (of the abdominal panel) can support my abdomen, compensates the pulling force and reduces the stretching on my back, and there is a rigid part (of the back panel) on the back for support... (P2, nurse aged 34)
One participant who has been using the maternity support belt (a different style from the garment samples in our study) throughout the current pregnancy felt that the wide band below abdomen and the belt pressure at low back centre were most useful to relieve the back pain. She suggested that the level of support would be affected by the band width and adjustability for suitable tension and fitting.
This abdominal band (pointing to her own maternity support belt) provides more support probably because it (the abdominal panel) is 2 inches wide…it (the abdominal panel) has to be at least 1.5 inches wide for better support…it will be good if it is adjustable because the position of the waist and the (back) pain region is different for different people. (P2, nurse aged 34)
Some participants felt that the supporting forces provided by the abdominal and the back panels were useful in reducing low back pain. One participant
80 explained that when she clasped their hands under the lower abdomen to provide an upward lift during walking, the vertical movement of the abdomen was reduced which seemed to lessen the strain over the back muscles.
4.3.2 Safety
40% of the participants expressed the concern about the safety issue when wearing the maternity support garments. Concern for fall was raised because there were two garment samples looked difficult to wear due to the non-stretchability of leg opening of the brief C (Figure 1c) and the complicated strapping design of the cradle G respectively (Figure 1g).
The lower part of the body is already bulky, this brief (the brief C) will be too tight and too difficult to wear and it is not safe for pregnant women to wear...(P3, housewife aged 30)
It (the cradle G) is difficult to wear during the later period of pregnancy…it (the cradle G) is inconvenient…I’ll trip (over the straps) and fall! (P1, teacher aged 35)
Another safety concern is that the tightness around the abdomen was perceived as a factor that may influence the fetus’s comfort and growth. Two participants were very sensitive to avoid any potential adverse effect to the fetus.
If it (the abdominal panel) is too tight then I will be concerned about my baby whether it (the pressure) will affect the baby’s growth. (P2, nurse aged 34)
It’s (the abdominal panel) so tight…I think it is not good for the fetus…it is best to provide more space for the fetus, that’s more comfortable. (P5, housewife aged 35)
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If I wear it (the maternity support belt) non-stop for a few hours, my baby will kick. He will kick me at the part where the belt is binding the body…the baby feels that something is pressing against him and he will always kick me. So I will make him feel comfortable as much as I can…If he is not comfortable, he will kick me. (P10, manager aged 36)
4.3.3 Skin comfort
All participants were felt a strong need for skin comfort as reflected by their concerns for itchiness, skin rash or infection. These conditions were thought to be caused by heat and humidity when wearing the maternity support garments due to the thick and non-breathable materials. They all preferred cotton fabrics because they felt that it has good water absorbent and heat transfer properties and is non-irritating to wear especially in the summer. The garment made of polyester and nylon was perceived as less breathable and uncomfortable because it might promote perspiration and skin rashes. 90% of the participants preferred soft and smooth fabric as it provides better tactile comfort for their sensitive skin.
I felt hot wearing it (the maternity support garment) when the weather became hot and I felt itching because of my bad skin, the sweating and the material is not breathable enough. It is very uncomfortable…it’s like my body is wrapped by something airtight…all the materials (in these maternity support garments) are very thick, all very thick…and it will cause bacteria to grow because the skin can’t breath and I will need to see the doctor to clear up the bacteria …because it’s easier for pregnant women to have (skin) infection...they (the maternity support garments) must be cotton, I must wear cotton…and it has to be thin, that will be much better…this kind of material (polyester)…causes infection more easily I think…Normally I am not bothered by the heat, but after I became pregnant, I began to be bothered by feeling hot and sweaty. I think that too tightly fitted (garment) will stick closely to the body, so when you sweat, the garment will become wet and sticks to the body making you feel uncomfortable. (P3, housewife aged 30)
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Cotton is the best…I need cotton because I already broke out into a lot of rash…so I wear low waistband pants…(otherwise) it makes me sweat and the sweat is not easily evaporated…but cotton absorbs sweat and is breathable…I don’t like material which is elastic because it is not breathable and makes me itchy…it is better if it (the material) can be softer… the edge is comfortable and smooth and won’t make me uncomfortable… (P5, housewife aged 35.
80% of the participants felt that the tight-fit abdominal panel would cause discomfort as the uterus grows. One even expressed concern about the pressure over the breasts which might cause discomfort.
This one (pointing to the abdominal panel of the vest H) seems to be too tight…there seems to be very little stretch…if your belly becomes bigger, then it (the abdominal panel) will be too tight and uncomfortable. (P3, housewife aged 30)
4.3.4 Ease to put on and take off
All of the participants preferred the garment to be simple and convenient to put on and take off because their movement became cumbersome with the enlarging abdomen.
This (the brief C) one is difficult to wear and the belly gets in the way…the lower part of the body is already bulky, this (the brief C) one will be too tight and too difficult to wear and it is not safe for pregnant women to wear...it’s difficult even when I put on underwear…before I am pregnant, I can just stand and wear it easily, now I have to sit on a chair first and then put it on slowly…(P3, housewife aged 30)
It (the cradle G) looks complicated. (P4, housewife aged 34)
83 This (the cradle G) is not very good (pause) I have to lift up my legs (pause) it’s quite hard for me…it’s quite inconvenient that we need to put it (the cradle G) on from the bottom. (P6, housewife aged 30)
4.3.5 Aesthetics
70% of the participants favored a simple style that is well-fitted to the body contour rather than something ‘odd’ with complicated looking like the cradle G. 80% of them preferred garments that look good. One participant said that fashionable is the most important element and two participants thought that sporty style looks good. Adjustable features were preferred for better fitting, convenience and value for the price.
Very strange…it (the cradle G) goes around the waist tightly as well as the shoulders…it makes you feel that your body is tied up…this (the cradle G) one is no good…I think this (the vest H) one is better, it (the vest H) looks like sports wear, yoga clothes…It’s better to look good and be simple (in style)...fashionable is the most important element. (P3, housewife aged 30)
40% of the participants preferred the maternity support garment to resemble an undergarment. One participant pointed out that wearing a maternity support garment that resembled the panty or vest was convenient because she did not need to wear two garments as underwear. For the accessories, the preference varied. Some participants liked ornaments but others did not because the laces have no support function and may cause skin irritation.
The vest looks good, I can wear it (the vest H) instead of wearing underwear…the ribbons and laces add no value and it is noticeable under the outer garment. (P5, housewife aged 35)
84 I don’t like the laces (of the brief B) as I get skin irritation easily. The style is okay yes… I like the shiny material more…I prefer the basic seams than to the lace seams. (P9, clerk aged 29)
60% of the participants liked the garment to be invisible under the outerwear and that no pressure marks were left on the skin after removal of garment (40%). The preference of invisibility of the garment seemed not only relate to the aesthetic outlook, but also with the desire of being viewed as ‘normal’.
The seams of the garment would be noticeable when I wear a tightly-fitted dress...it’s not pretty…the crossing over makes it (the belt F) bulky at the back and it (the belt F) will be noticeable…I want a smooth body shape. (P4, housewife aged 34)
The style is okay because it’s (the vest H) just like the underwear, people won’t notice that you are wearing it (a special garment). (P3, housewife aged 30)
Almost all the participants have commented on the colors and had their own preferences. The most preferred choice was skin color or light color for example, white, pale pink and pale yellow for both aesthetic and practical reasons. One participant liked white because it feels clean to wear and it is easier to bleach whereas another participant preferred a darker color because it does not easily get soiled.
Skin or pink color is okay because they will not be shown through even if I wear thin layered clothing…I think the skin color is easier for mix-and-match. (P2, nurse aged 34)
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4.3.6 Functional and aesthetical needs
Based on the interview data, the expressed values of maternity support garments could be summarized into functional and aesthetical aspects (Table 4.2). Some participants believed that aesthetics value was secondary when compared with the functional value of maternity support garments. However, others commented that unless the pain was severe enough to require such garments, otherwise they would prefer tolerating the pain rather than wearing the medical garment that looks strange.
I think the style is not a great problem. I think that usually the maternity support garments do not look as nice as the normal underwear…but the function is more important…I will choose the one that has a better function than the one that has a better appearance. (P10)
Actually I think that the appearance is not so important as I wear it beneath the outerwear so on no can see it. But, I think it’s more important to see whether it’s functional. (P7, clinic assistant aged 37)
Close to the completion of the interview, the participants were asked to rank the order of precedence when using or buying a maternity support garment. Different women had different opinions (Figure 4.2). While 70% of the participants ranked the function as the first or second priorities, many others perceived that ease to put on and take off (100%), comfort (90%), water absorbent and heat transfer properties of the fabric (80%), and non-itchiness (70%) were crucial. When compared to the functional values, aesthetics in terms of color and design (20%) became less significant.
86 Table 4.2 Functional and aesthetical values of maternity support garments Functional values Aesthetic values Provide back pain relief Provide a simple and appealing style Provide optimal support to the abdomen Provide favorite colors Provide optimal support to the lower back Provide resemblance to an undergarment Diminish excessive pressure on the abdomen Minimize bulkiness of garment Provide good air circulation to the skin Minimize visibility of garment Diminish moisture on the skin Diminish irritation on the skin Diminish pressure on the skin Facilitate ease in dressing and undressing Facilitate convenience for toileting
120 5th rank 4th rank 100 3rd rank 2nd rank 80 1st rank
60
40
20
Percentage (%) of participants 0
t l f es tion or chy of y) i c it teria e ert un a p F Comf on M to move ro N nd tak m p a , durabilit er n edo t o re colour and design) , price F pu le t transf cs ( o ea mp h xa d stheti Ease t e an Ae for bent or
er abs at iscellaneous ( W M
Figure 4.2 Participants’ responses in ranking the order of precedence of garment characteristics when using or buying maternity support garments
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4.4 Discussion
The results confirmed that women’s physiological and psychological changes during pregnancy influenced their clothing preferences on both functional and aesthetical values. The principal findings of this study are five main themes of pregnant women’s needs, concerns and problems when using maternity support garment. They are effective function, safety, skin comfort, aesthetic and ease to put on and take off. The findings were largely consistent with previous studies examining medical garments for overall satisfaction and compliance (Johnson et al., 1994; Myers et al., 1995; O'Hare, 1997; Williams et al., 1998).
A notable finding is that all participants who have used the maternity support garment for the relief of LBP were self-prescribed instead of seeking advice from healthcare professionals. This practice is congruent with self-care behavior in response to musculoskeletal pain and its interference on the performance of daily activities (Dannecker et al., 2007). Since over-the-counter analgesics are contraindicated during pregnancy and pregnant women are wary of taking even recommended medications (Carr, 2003), the maternity support garment is a convenient and easily accessible alternative.
The factors that had the largest influence over the decision to use maternity support garments were advice from friends, relatives, and maternity fashion store personnel. Evans et al. (2007) reported similar findings that as a result of lack of complimentary and alternative medicine information from health professionals, patients acquired ‘alternative’ information sources and treatment options through the network of trusted family, friends and acquaintances. It implies that healthcare professionals should play a role in guiding patients to make better informed choices.
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4.4.1 Effective function
Perceived effectiveness in the pain relief and support function of maternity support garment largely affected the decision making process of the participants in this study in buying and/or using the maternity support garment. Previous studies of other garment therapies also found that non- compliance with treatment was due to a lack of perceived benefits or improvement (Hubbard et al., 2000; Sawada, 1994). Despite the majority of participants have purchased and/or used the commercially-available maternity support belt, only a small percentage (30%) of the participants in this study were compliant to the garment therapy as they reported some perceived benefit from the treatment. It raises the concern whether this perceived benefit is a placebo effect or it has genuine therapeutic value, which needs to be investigated in future studies.
4.4.2 Safety
Some participants expressed their concern for the restrictiveness of the abdominal panel with the perception that the tension may be harmful as it elicited increased ‘kicking’ movements from the fetus. The concern for safety may reflect pregnant women’s anxiety and fear regarding their own health and their babies (Colman & Colman, 1990). It is important that pregnant women have comparable information about risks and benefits of the treatment options to weigh. With advice from the healthcare professionals, they can make appropriate treatment decisions suitable for their individual needs. Future studies into any adverse effects or complications in the use maternity support garments are necessary.
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4.4.3 Skin comfort
The compliance of therapy was usually affected by skin discomfort due to excessive heat, itchiness, excessive pressure, and inconvenience of adjustment. The greater need of pregnant women for skin comfort can be explained by their physiological changes during pregnancy including excessive perspiration, elevated body temperature and increased skin sensitivity (Cherry & Moss, 2004). The fabric played a very important role in maternity support garments not only to promote skin comfort but also to provide optimal support. A comprehensive test of the fabric mechanical and surface properties is a meaningful study to identify the optimal fabric material that demonstrates a good balance between skin comfort (soft, smooth, breathable attributes) and the support function (rigidity and adjustability) for proximal fit maternity support garments.
4.4.4 Ease to put on and take off
Most of the participants preferred a simple and convenient ergonomic design that facilitates dressing and undressing, and for toilet use as pregnant women experience frequency of urine particularly during the first and the third trimesters. It is plausible as pregnant women experience movement limitations and postural imbalance (Gilleard et al., 2002a; Nicholls & Grieve, 1992), which affects the daily activities such as getting dressed and undressed (Nicholls & Grieve, 1992). Complicated garment application that requires forward bending and balancing not only imposes the risk of fall but also was perceived as difficult to wear. Future study on the motion analysis of pregnant women in using maternity support garments will provide more in-depth knowledge about the biomechanics of how the garment supports the body and facilities the wearer’s daily activities.
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4.4.5 Aesthetics
Many participants desired for aesthetic appearance when wearing the maternity support garment whereas some participants had less concern since the garment is covered by the outerwear. This was reflected by their preference in garment attributes including ‘looks good’ and fashionable, invisibility of garment, well-fitted, and favorite colors. Previous studies also found that the style that ‘look good’ was important to pregnant women (Chan, 2000; Johnson et al., 2004) and that the maternity support garment that appeared odd, ‘medical-looking’ and old fashioned was disliked (Johnson et al., 2004; Yu & Wong, 2001).
The strong desire for aesthetic appearance in clothing among some pregnant women may be partly explained by the women’s negative attitudes towards the images of their bodies as they experience dramatic changes in the body weight and shape during pregnancy. Some women used negative terminology to describe their pregnant bodies as ‘fat’ ‘ugly’, ‘frumpy’, ‘bloated’, ‘weird’ and referred to being less attractive (Johnson et al., 2004). Recent studies found that clothing may play a role in the enhancement of self concept (Sweeney & Zionts, 1989) and that women who were more dissatisfied with their bodies were more likely to engage in clothing-related appearance-management behaviors such as wearing apparel to camouflage their bodies and avoiding revealing (Trautmann et al., 2007). An interesting finding is that some pregnant women seem to exhibit similar behavior to help in boosting their self-images which needs to be confirmed in future studies.
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4.4.6 Functional and aesthetical needs
Consistent with previous studies, the function of therapeutic garment is perceived as one of the primary factors that influences women in using or purchasing maternity support garment (Chan, 2000; Myers et al., 1995; Yu & Wong, 2001). Other functional values such as providing skin comfort with non-itchy, breathable and moisture absorbent materials are the most important parameters in the future garment design as they affect the compliance of wearing maternity support garment. For some individual preferences, the availability of colors and aesthetic design will also be of importance.
4.5 Conclusion
This study identified the needs, concerns and problems in the use of maternity support garment. Five main themes of specific ergonomic needs were found by in-depth interviews with pregnant women. They include the effectiveness of function, safety, skin comfort, ease to put on and take off and aesthetics of the garment. With detailed content analysis, new knowledge has been developed about the pregnant women’s needs for maternity support garment, the desirable features and the problems associated with maternity support garments. This study was limited to the interviews of a small sample of Asian women.
Data presented in this chapter has been presented in Garment needs of pregnant women based on content analysis of in-depth interviews. Journal of Clinical Nursing (under review).
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CHAPTER 5
COMFORT EVALUATION OF MATERNITY SUPPORT GARMENTS IN WEAR TRIALS AND MATERIAL TESTS
5.1 Introduction
This chapter presents the wear trials and material tests in the exploratory phase of the study. Eight commercially-available maternity support garments were evaluated by 14 pregnant Chinese women. The thermophysiological, sensory/tactile and movement comfort were assessed using a 19-item questionnaire. Fabric objective measurements of the 8 tested garments were obtained to reveal the role of fabric properties in comfort responses.
5.2 Methods
5.2.1 Garment samples
The maternity support garments in this study include four main types; belts, briefs, cradles and vests (Ho et al., 2006; Yip & Yu, 2006). The maternity belt is a wide panel of padded fabric. It is usually worn under the lower abdomen and wrapped around the waist. Extending from the abdominal panel are the side panels which are sometimes designed to intersect at the lower back and extend to the front panel with velcro tape fastening. This allowed a large range of fit for varying abdominal circumferences. The maternity briefs cover the wearer’s abdomen and hips with both waist and leg openings. It usually has a fold-over inelastic panel to provide additional warmth and support to the lower abdomen. The tension of this abdominal panel was adjustable at both sides of the upper hip by velcro tapes. The cradle consists of shoulder straps, abdominal panel and side panels, which
93 are worn over the wearer’s shoulders to assist the abdominal band in supporting the growing abdomen by redistributing the uterine weight across the upper torso. The maternity vest covers the upper torso with a belly panel of soft extensible fabric and an abdominal support panel at the lower abdomen. Within each type, there are variations in the design and the materials used.
Eight commercially-available maternity support garments were evaluated in this study including two belts, four briefs, one cradle and one vest. They were all claimed to provide support to the pregnant women’s abdomen and back by the salespersons of the maternity shops where the garments were purchased. The detailed features of each garment sample were described in Figure 4.1 in the previous Chapter. The eight samples were selected according to three criteria. Firstly, at least one style was available for each type. Secondly, the garment design should appear to provide support to the abdomen and/or the back. Thirdly, different main materials and style features were involved. Ten garments were initially selected for the pilot study. The number of samples were reduced to eight because some samples had similar features and too many samples would make the wearers exhausted and lose interest in the wear trial (Saville, 1999).
5.2.2 Subjects
Initially 20 pregnant Southern Chinese women were invited to participate by convenience sampling from the Obstetric Clinic of Queen Mary Hospital (QMH). This study followed the Code of Ethics for Research Involving Human Subjects. Ethical approval was obtained from both The Hong Kong Polytechnic University and QMH. Written consent forms were signed by the subjects and the procedures of wear trials and questionnaires were fully explained prior to the study. The recruited pregnant women were able to communicate fluently in Cantonese. Those with twin pregnancy, a known history of spinal disease or surgery, or chronic LBP were excluded. Among the women, two declined to participate due to tiredness and four were excluded because of carrying a twin pregnancy or a history of spinal disease.
94 Therefore, the final sample consisted of 14 pregnant women aged 32.3 ± 4.2 (mean ± S.D.).
5.2.3 Wear Trial Procedure
The abdominal and hip circumferences of all subjects were measured so that the correct sizes of maternity support garments were provided. Each subject was allowed to choose at random the sequence of wearing the eight samples. The same researcher provided the pictures and the standardized procedures of wearing. The wear trial was conducted in an environmentally controlled room, an air-conditioned room with temperature maintained at 22 ± 2°C. Sufficient time and privacy were provided so that the whole process was conducted in a relaxed environment. Each trial lasted for 45 minutes to an hour. To minimize recall bias, all subjects were required to provide a comfort score and a reason for each item when appropriate while putting on the garment sample, wearing it, performing six specified activities (standing, sitting, walking, bending, squatting, and twisting), and taking off the sample. These movements represented a reasonable range of ‘normal’ conditions for pregnant women. The subjects were allowed to adjust the scores at anytime during the trial.
Due to the lack of resources and time, it was not feasible to study garment samples overtime. Wearing the garment for a day or more may allow the women to gain a better ‘feel’ of the garment in a more realistic environment such as home and/ or workplace. This may enhance the accuracy in ratings. On the other hand, it would be difficult for women to make score adjustments when comparing between the earlier and latter samples due to recall bias. Also, extraneous variables such as amount of activities, outerwear, and wearing time would need to be controlled for a study over a period of time.
5.2.4 Comfort evaluation
95 This study evaluated the perceived comfort responses in maternity support garments in three main dimensions: thermophysiological, sensory/tactile and movement. Thermophysiological comfort concerns the maintenance of body heat balance (Fourne, 1999). The skin sensation of fiber and fabric influences the wearer’s perception of comfort through the garment’s transferability of bodily heat and permeability of moisture vapor, especially in the hot climate of Southeast Asia. Sensory comfort relates to the softness and smoothness of fabric and finishing. Unpleasant sensations include tickle, prickle, and itch (Bartels, 2006; Saville, 1999). Tickle is caused by the fabric hairiness and prickle is due to the coarse and stiff fibers protruding from the fabric surface. Materials that contain allergic properties such as laces, rubber straps, metallic or plastic fasteners may also cause skin irritation and itchiness.
Comfort during movement was also studied. The convenience of putting on or taking off the garment is affected by the design of style lines, pattern cutting, stretchability of fabric, dimensions of components, use of fastenings and the assembling method. Too narrow cut of openings for the neck and arms, too rigid panels along the hem under abdomen, or insufficient stretch ability of waist elastics, would be more restrictive to put on and take off, and hence may be perceived as less comfortable to wear. A total of 19 items regarding wear comfort were included in the wear trial evaluation questionnaire (see appendix 18).
5.2.5 Magnitude scaling
Magnitude scaling method has been regarded as a useful research tool to examine human sensory and comfort responses to clothing and textiles (Ali & Begum, 1994; Sweeney & Branson, 1990). Magnitude scaling is reported to have the advantages of greater accuracy in gauging the strength of sensations and providing the respondents with continuous response measures (Lodge, 1981). Traditional comfort scales were basically designed for individuals with normal body temperature and skin sensitivity. However, pregnant women typically exhibit elevated body temperature and increased
96 skin sensitivity (Leifer, 2005). The high sensitivity to the perceived thermal and tactile comfort is therefore better measured by the more sensitive magnitude scaling method.
Magnitude scaling allows subjects to assign their own numbers to represent the magnitude of their comfort sensations (Albaum et al., 1981). Those numbers may be more meaningful as the subjects are not forced to fit their scores into a narrow pre-determined range such as a Likert scale. Comfort is a complex evaluative and affective dimension (Cardello et al., 2003). The same garment characteristic may elicit different comfort responses from different individuals.
After an explanation was provided to all subjects with regard to the magnitude scaling method, they were asked to assign two numbers, one representing the “best” score and the other the “worst” score. The score given to each comfort item must be between the two preset numbers. The scores were then normalized between 0 and 10 in the data analysis. Higher score denotes a greater degree of comfort or a more desirable quality. In the scale of transformed values, point 5 was used to denote neutral. It is noted that there is slight asymmetry between the scores of comfort and discomfort, in that the interval between neutral and somewhat comfortable is not perceptually equivalent to the interval between neutral and somewhat uncomfortable (Cardello et al., 2003).
5.2.6 Internal consistency
The internal consistency of the wear trial evaluation questionnaire was assessed using Cronbach’s alpha. As a rule of thumb, it requires an α ≥ 0.70 and ≥0.20 to show an acceptable internal consistency of an instrument (Portney & Watkins, 2000b). In this study, the Cronbach’s alpha α = 0.95 and the mean correlation coefficients = 0.66, with a range from 0.40 to 0.83 between all items. Therefore, the scoring system was regarded as reliable with high internal consistency.
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5.2.7 Data analysis
Descriptive statistics of the 19 normalized comfort scores for 8 garments given by 14 subjects included means and standard deviations. Histograms and line charts were used to illustrate the preferences for each garment design and the comfort scores in various activities respectively. Spearman’s correlation was used to investigate the relationships between the subjective comfort variables.
5.3 Results
The results of wear comfort are presented in three dimensions; thermophysiological comfort, sensory/tactile comfort, and comfort during movement.
5.3.1 Demographic data
For the 14 subjects recruited, their mean age was 32.3 ± 4.2 years (range 23- 39). Their mean gestation at study was 30.2 ± 5.9 weeks (range 21-36). Ten subjects (71.4%) had not previously given birth; two (14.3%) had one child, and two (14.3%) had two children. Most subjects (80%) were working full time. Their occupations were clerks/administrators (37%), health professionals (14%), teachers (14%), and salespersons (14%). The high percentage of working women is consistent with the census data revealing the increasing trend of working women in Hong Kong, particularly those with higher education (Census and Statistics Department, 2008).
5.3.2 Magnitude scaling
All subjects assigned a smaller number as the worst score and a greater number as the best score for the scoring system. The women in this study tended to use a 5 to 11 point scale to differentiate their perceived comfort. The scale of 0 to 10 (11 points) was used by most subjects (71.5%) while
98 21.4% of the subjects preferred 1 to 5 (5 points), and one subject placed scores between 50 and 100 (6 points). Sensory scaling studies have suggested that 10-point scales can provide sufficient levels of discrimination (Jensen et al., 1994), and that a scale of less than five points can result in a loss of discrimination sensitivity (Cardello et al., 2003). The data confirms that the magnitude scaling was a useful method to measure comfort variables in maternity support garments in this study.
5.3.3 Thermophysiological comfort
Figure 5.1 shows the comparison of the mean scores in the perceived thermal and moisture comfort (n=14). The scores were distributed in a narrow range between 5.0 and 7.2, with the mean scores of 6.1 ± 1.7 and 5.8 ± 1.7 for thermal and moisture comfort respectively. Sample D was rated the highest scores 7.2 ± 1.6 in both thermal and moisture comfort, whereas sample B was perceived as the poorest in thermal (score 5.3 ± 1.6) and moisture comfort (5.0 ± 1.9). The relationship amongst subjective scores within perception of thermal and moisture comfort sensations were also investigated. The results show that there was a strong correlation (r=0.80, p<0.001) between thermal and moisture comfort.
10 Heat transfer 9 Moisture transfer 8 7
6 5 4 3 2
1
best) 10: worst, (0: score Mean comfort 0
Belt F Belt Belt E Belt Vest H Vest Brief A Brief B Brief C Brief D Brief CradleG
Figure 5.1 Mean (S.D.) comfort scores of heat and moisture transfer
99 5.3.4 Sensory/tactile comfort
The mean scores of the eight garment samples on material quality and hand feel before wearing, and the scores reported on non-itchiness and no red marks after wearing are presented (Table 5.1). In general, the mean score of sensory/tactile comfort (6.8 ± 1.8 for material appearance and 6.9 ± 1.7 for hand feel) was rated higher than the thermophysiological comfort (6.1 ± 1.7 and 5.8 ± 1.7 for thermal and moisture respectively). Sample D had the highest scores of 7.7 ±.1.1 for material appearance and 7.9 ±1.0 for hand feel whereas sample G scored the lowest in both items (5.2 ± 2.2).
Table 5.1 Mean scores of sensory/tactile comfort Garment Before wearing After wearing Material Handfeel Non- No red mark itchiness A 7.6 (1.4)1 7.8 (1.3)1 7.8 (1.3)1 7.8 (1.8)3 B 5.9 (2.1)1 6.0 (2.0)1 5.6 (2.2)1 6.5 (2.2)2 C 6.8 (1.7)3 7.1 (1.5)3 6.9 (2.0)4 6.1 (2.3)5 D 7.7 (1.1) 7.9 (1.0) 7.9 (1.1) 8.0 (1.3)1 E 6.8 (1.4) 7.0 (1.1) 6.5 (2.1) 6.9 (1.6)1 F 7.3 (0.7) 7.2 (0.7) 7.3 (1.7) 7.4 (1.7)1 G 5.2 (2.2) 5.2 (2.2) 5.7 (2.3)1 5.7(2.3)2 H 7.2 (1.7) 7.1 (1.7) 7.7 (1.5)1 6.9 (2.3)3 Data are presented as mean (SD); 1-5 = Number of missing data
The correlation coefficients (n = 107, df = 105) among the scores on sensory/tactile comfort before and after wearing the garments are shown in Table 5.2. A significant correlation was found between the scores on material appearance and hand feel (r = 0.86, p<0.001), and between the scores on the non-itchiness and absence of red marks (r = 0.78, p<0.001),
100 but there was only a moderate correlation between hand feel and no red mark (r = 0.52). Figure 5.2 shows a strong correlation between the subjective score of material quality by observation and the physical comfort score of hand feel.
It is important to note that the missing data resulted from the subjects refusing to wear the garment as they perceived that garments were difficult to put on. In this respect, the brief C had the highest number of missing data because it consisted of ‘narrow’ leggings with fabrics of poor stretchability and were perceived as ‘too tight’ making it difficult to put on. This limits the comparability of the brief C with the other garments in this study.
Table 5.2 Spearman’s correlation matrix of sensory/tactile comfort (n = 105) Non-itchiness No red mark Material Handfeel Non-itchiness No red mark 0.78** Material 0.38** 0.43** Handfeel 0.44** 0.52** 0.86** **P<0.001
10
9 8 7
6 5
Hand feel Hand 4
3 2 1 0 0 1 2 3 4 5 6 7 8 9 10
Material appearance
Figure 5.2 Scatter plot for the mean scores of material appearance and handfeel (n=107)
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5.3.5 Comfort during movement
Figure 5.3 shows the mean comfort scores of 8 garment samples during the 6 common activities carried out by the pregnant women. The mean scores ranged from 5.3 to 7.5 and standard deviation ranged from 0.8 to 2.3 for each garment during the 6 specified activities. Briefs A and D were rated relatively high (score 7.1 and 7.0 in average respectively), while brief B and cradle G had the lowest scores close to 6.0.
10 Standing Sitting 9 Walking Bending 8 Squatting Twisting 7
6
Mean comfort score (0: worst, 10: best) 10: worst, (0: score comfort Mean 5
E t G t H el e s rief C rief D Belt F dl Brief A Brief B B B B a Ve Cr
Figure 5.3 Mean (S.D.) comfort scores during the six specified activities
102 As shown in Figure 5.4, samples A, D, E and F were easy to put on and take off, with scores close to or above 7.0. Samples C, G & H showed scores below 6.0 indicating that they were more difficult to put on and take off. Regarding convenience for toileting, samples D, F and H performed better with scores above 7.0.
10 Ease to put on 9 Ease to take off Convenience for 8 toileting
7
6 5
4
best) 10: worst, (0: score comfort Mean A B G H f C lt F ie ief e le st ief rief D B e Br Br Br B Belt E V Crad
Figure 5.4 Mean (S.D.) comfort scores of ease to put on, take off and convenience for toileting
103 5.3.6 Overall comfort
Figure 5.5 presents the mean comfort scores of each garment sample in all the 19 comfort variables. It shows that brief D was rated the best product (score 7.39 ± 0.56) and cradle G was considered the worst (score 5.65 ± 0.57).
10
9
8 7.4
7 7.1 6.9 6.8 6.6 6.3 6 5.9 5.7 5
4 Mean comfort score (0:worst, 10: best) A F H D lt G ef B ef C ef e le st ri ri B d Brief B Bri B Belt E ra Ve C
Figure 5.5 Overall mean comfort scores of each maternity garment sample
104 When comparing the 4 maternity briefs in Figure 5.6, samples A and D were much better than B and C in all comfort items. If score 7 is considered as ‘good’, brief D was at least ‘good’ for material, hand feel, invisibility, sitting, walking, twisting, freedom to move, no itchiness and red mark. Also, it was very easy to put brief D on and take it off and it was convenient for toileting.
Appearance When wearing During movement When taking off 8 Brief A
Brief B Brief C 7 Brief D
6
5
Mean comfort score (0:worst, 10: best) 10: (0:worst, score comfort Mean
4
Sitting Design Material Twisting Walking Bending Invisibility Standing Handfeel Squatting Freedom Appearance mark red No Heat transfer Heat Non-itchiness Ease to put on Easeto take off Moisture transfer Convenience toilet Convenience
Figure 5.6 Mean comfort scores of each assessment item of the brief samples
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5.4 Discussion
5.4.1 Thermophysiological comfort
Thermal moisture comfort factor is one of the three major sensory factors that influences the perception of clothing comfort and explains about 50% of the total variance of comfort (Wong et al., 2002). The critical needs of thermophysiological comfort in pregnant women are due to several physiological changes during pregnancy. Pregnant women experience an increase in body temperature, perspiration and skin sensitivity (Leifer, 2005) and the risk of developing heat intolerance and skin rash increases (Cherry & Moss, 2004). Also, increased thermal and humid microenvironment of clothing can change the skin climate. Studies have shown that altered temperature, humidity and pH can become a favorable environment for skin microflora to cause skin reaction and infection (Akin et al., 2001; Aly et al., 1978; Lukacs et al., 1995; Rippke et al., 2002; Runeman et al., 2000; Runeman et al., 2004). Therefore, thermophysiological comfort of maternity support garments is essential in the promotion of skin health in pregnant women.
The results indicate that all the eight commercial samples seem unable to provide a high level of thermal and moisture comfort but are somewhat acceptable in thermophysiological properties. Samples A and D, containing cotton or cellulose material like viscose (Table 5.3), provided better thermophysiological comfort than samples B and C, which were made from nylon and polyester. Sample G, which contains only 9% cotton (Table 5.3) and covers a small area of the body, was shown to be inadequate in moisture absorbing with a mean score of 5.1 ± 2.0. However, if the nylon fabric were treated with a special finishing, the skin sensation might have been greatly improved. Sample H, although covering a large area of the upper torso and was a synthetic combination of nylon and spandex, was rated almost as high as sample A which contains viscose (6.3 ± 1.6 and 5.9 ± 1.4 for thermal and moisture comfort respectively). The finding of a significant correlation
106 between the perception of thermal and moisture comfort responses was consistent with the study by Wong and Li (2004).
The findings reveal that the perceived thermal and moisture comfort is not influenced by the garment type or the design, but rather it is largely influenced by the fiber contents and fabric breathability which was related to the thickness and porosity influenced by knitting construction. Both samples B and D belonged to the same brief category consisting of squared legs and a covering for the whole abdomen. Their major differences were the fiber contents (B uses 100% nylon and D uses 70% cotton & 30% elastane), the fabric thickness (B has 2.6mm and D has 1.4mm in average) and air permeability (B has 133 cc/sec/cm2 and D has 66.7 cc/sec/cm2 in average) (Table 5.3). Likewise, samples E and F are both belt types with similar bowl shaped cradle to accommodate the growing abdomen. Sample F scored slightly better in heat comfort than sample E because sample F has a thinner fabric than E (E has 3.5mm and F has 2.7mm). Although sample E is thicker than F, moisture comfort in both belts received similar scores of close to 6.0 because sample E is lined with fabric that contained cotton.
Sample D containing the highest cotton content and a thin fabric was most preferred by the pregnant women in this study. Horridge et al. (2002) found that comfort scores were affected by fiber content. Bartels (2005) showed that the preference for hygroscopic fibers such as cotton or non-hygroscopic fibers such as nylon was dependent on the amount of sweating. In a condition where liquid sweat was produced by the wearer, for example during exercising, non-hygroscopic fibers were the better choice due to their ability to dry quickly and to transport moisture through the fabric. In the case of pregnant women where mainly vaporous sweat was produced because of the low activity level and air-conditioned environment, hygroscopic materials like cotton were better alternatives.
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Table 5.3 Fabric properties of maternity support garment samples
Fabric content Fabric structure Thickness Air (mm) permeability (cc/sec/cm2) Outer Inner A 60.5% Nylon 1.7 180.0 30% Viscose 9.5% Spandex B Nylon 2.6 133.0
C Polyurethane 1.7 31.0 Nylon
D 70% Cotton 1.4 13.1 30% Elastane
E Polyester 3.5 51.0 Cotton
F 45% Nylon 2.7 133.4 15% Polyester 15% Spandex 17.5% Cotton 7.5% Rayon G 64% Polyester 2.5 27.7 23% Spandex 9% Cotton 4% Nylon H 82% Nylon 1.0 269.0 18% Spandex
The data are presented as mean.
108
5.4.2 Sensory/tactile comfort
Increased skin sensitivity is often seen in pregnancy and pruritis (itchiness) is the main dermatological symptom (Weisshaar et al., 2005). Clothing with irritating or allergic substances that are worn close to the skin can elicit skin reactions (Ho et al., 2005). Skin reaction can vary from mild irritation and redness to open sores, depending on the type of irritant, the body part affected, and the sensitivity of the individual. Other symptoms include skin inflammation (localized swelling and warmth), tenderness and skin rash or lesions in the exposed area.
The material quality and hand feel of maternity support garments would affect the sensory/tactile comfort. The evaluation of material quality involved the subject’s visual perception and hand feel was a direct subjective sensation that arose from skin contact with fabrics. This is often expressed as softness, stiffness, smoothness, roughness, prickliness, dampness or clinginess. The findings showed that the eight samples were perceived to provide a greater degree of comfort in terms of skin touch than that of heat and moisture transfer.
For sensorial comfort, the soft and smooth sensation of sample D scored the highest for material quality and for hand feel whereas the rigid, non- breathable and frictional sensation of sample G had the lowest scores for both items. One subject even developed itchiness and a mild skin rash over her abdomen while wearing sample G. Some subjects commented that sample B gave rise to a prickling sensation in the sensitive area of the groins because of the lace material around the leg openings.
The subjects’ visual perception of material quality was highly correlated with the physical hand feel. This indicates that the pregnant women participated in this study were very sensitive to the comfort value of material. The positive correlation between hand feel and no red marks indicated that a better hand feel in the fabric led to the absence of red marks.
109 Less satisfactory hand feel with a score of 5 or below would tend to cause red marks whereas a better hand feel with a score of 6 or above would avoid the problems of red marks. It is suggested that hand feel was not the only factor affecting the comfort in wearing. Other factors such as material properties of stretch and garment tension might have also contributed to tactile comfort.
5.4.3 Comfort during movement
Wear comfort during movement is important for pregnant women in a modern society as they are a part of the work force and they need to remain active in their daily life. As pregnancy advances, women experience reduced range of motion and postural balance due to the increased trunk mass and dimensions and the shifting of centre of gravity (Bullock et al., 1987; Franklin & Conner-Kerr, 1998; Gilleard et al., 2002a; Golomer et al., 1991). This restriction of motion and postural instability makes daily activities such as putting on and taking off clothing (Cheng et al., 2006), which involve forward bending movement, more difficult to perform. Comfort during movement is influenced by the fabric stretchability, cut pattern and garment assembly (Bartels, 2006; Li & Wong, 2006). Garments with too narrow openings or insufficient fabric stretch may be restrictive to movements and create difficulty in putting on and taking off the garment.
The finding of significant correlation between the overall mean freedom of movement score and the mean score of the six specified activities indicated that the pregnant women were very sensitive towards comfort for both general and specific situations. It is interesting to find that the garment type and style features affect the comfort in movement. For example, samples E and F seem to provide the greatest degree of comfort during movements among the eight samples because they are worn just around the waist. Both belts were comfortable to wear for all activities, although some subjects found the belts uncomfortable when bending forward because of the bulky abdominal padding.
110 Both samples A and D had high scores and were made with a soft and thin material for the abdominal panel even though they have a wide front panel to support the lower abdomen. In contrast, sample C with long legs and strong tension around the buttocks was rated slightly lower especially in bending forward (6.2 ± 1.7). The sample B was rated the most uncomfortable (6.2 ± 1.7) due to the large and thick bowl-shape panel which was a burden and created restriction to the wearers especially in sitting and bending (5.7~5.8). Sample G was also uncomfortable to wear (6.1 ± 1.5) in all six activities because the relatively stiff abdominal band tended to cause discomfort by localizing pressure over the abdomen and that the elastic bands over the torso made the wearer felt “tied up”.
Samples A and D are briefs with soft materials, while E & F are belts. The findings show that garment design is the main factor affecting the ease of putting on and taking off the garment. Samples C and H were found to be difficult for putting on and taking off due to the tight fitting with high fabric tension. Subjects required greater effort to extend the material before getting into the garments. Sample G was the most difficult to be worn (4.9 ± 2.3) because it was too complex. One subject refused to wear it and another subject feared that she might trip over the elastic bands. Sample H was difficult to wear (score = 5.7 ± 2.4 for easy to put on and 4.3 ± 2.6 for easy to take off) because it was tightly fitted, but was very convenient for toileting (7.8 ± 1.9) since it did not need to be taken off. The results reveal that garment tension and complexity reduced the perceived comfort responses during putting on and taking off of garments, which is important to pregnant women because they need frequent toileting due to the compression of the bladder (Leifer, 2005).
111
5.4.4 Overall comfort
Overall, the pregnant women favored briefs A and D because probably due to the fabric contained cotton or viscose and the garment smoothly fitting on the body. Brief B had a bulky front panel and brief C had long legs and was considered too thick, tight, hot and humid, visible and difficult to bend forward in. Despite of the perceived thickness, belts E and F were generally acceptable because the wearers found it easy to put them on and take them off. The wearers could also move freely when wearing the belts and they were convenient for toileting. Cradle G was most disliked because it looked odd and clumsy to wear; the materials were poor in hand feel and moisture transfer. Vest H was perceived as basically fine, and was rated well on material, invisibility and toileting, but it was difficult for people to pull over the shoulder.
5.5 Conclusion
To conclude, the wear trial using magnitude scaling was useful for the evaluation of various garment attributes that may affect the perceived comfort including thermophysiological, tactile, and movement comfort. For thermophysiological comfort, the fiber contents and breathability of material including porosity and thickness were the major determinants. Cotton or Viscose fabrics were more comfortable than nylon and polyester for pregnant women in this study.
For tactile comfort, only soft, smooth and breathable materials were preferred. Itchiness that led to scratching was intolerable. The subjects generally experienced a greater degree of comfort with respect to the hand feel rather than the thermal and moisture transfer when wearing maternity support garments. The visual perception of material and the comfort response of hand feel were significantly correlated, but the correlation between hand feel and red mark was only moderate. Significant correlations were also found between non-itchiness and absence of red-mark. Rough
112 edges and materials such as laces can elicit undesirable itchiness and scratching.
For comfort during movement, the mean comfort score on the six specific activities was significantly correlated with the overall perceived freedom of movement. Among all the samples, the belt types and good-fit briefs provided a greater degree of comfort during movements, and were perceived as easier to put on and take off. The cradle containing complicated cross bands was perceived as difficult to hold in place and not easy to move in. The vest was perceived to be easy to move in and the most convenient for toileting, but was difficult to pull over the shoulders.
Overall, brief D was the best maternity support garment among the 8 samples due to its superior material thermal and moisture transfer, soft and smooth hand feel, simple style and invisible, and stretch fitting that allowed easy movement and convenience for toileting. This study provides data to support a better understanding of the effects of garment attributes on various aspects of comfort. The findings can be used to facilitate the design and development of special functional garments with the aim to satisfy critical ergonomic needs.
The methods and data presented in this chapter have been published in Ergonomics 51(9): 1376-93. (2008).
113 CHAPTER 6
PROTOTYPE DEVELOPMENT OF MATERNITY SUPPORT VEST FOR THE RELIEF OF LOW BACK PAIN DURING PREGNANCY
6.1 Introduction
This chapter presents the design and development process of maternity support vest prototype for the relief of PLBP. The DeJonge’s functional design model was used as the conceptual framework to design, develop, and evaluate the garment prototype. A set of comprehensive design criteria is highlighted with detailed design specifications. These design criteria were identified through systematic in-depth interviews (Chapter 4), subjective comfort responses in wear trials (Chapter 5), and objective material tests (Chapter 5). The results of material tests were used to guide the appropriate material selection. Based on the design criteria and specifications, the prototype style, pattern, fabric and cutting was developed and evaluated by live pregnant models and fitting experts.
6.2 Design model
To develop new design criteria and garment prototypes for maternity support garments, it is necessary to employ a clothing product design and development framework to guide specifically-designed research in a systematic manner. Among the existing frameworks as previously described in Chapter 2, DeJonge’s functional design process was often used by clothing and textile researchers to guide research concerning the development of garment design criteria and prototype. Examples of previous research that have used the full, or adaptations of, DeJonge’s basic design framework are clothing for women with physical disabilities (Carroll, 2001), intimate apparel designs for women (Chan, 2001) and hospital clothing for neonates (Bergen et al., 1996).
114 DeJonge’s (1984) suggested that the goals of design process must be explicated so that the resulting design meets the specific needs (DeJonge, 1984). The framework is divided into seven steps of design processes as presented in Table 6.1. Applying DeJonge’s model to this study, our design process was outlined from initial request to the evaluation of garment prototype. It allows the designer to apply the process to any functional clothing design project at any phase of development. At the early stage, the designer should explore as many directions as possible and allow the possibility of a redefinition of the design problem. The next step is a more in-depth research of specific factors influencing the design. This systematic model is useful for the designers to determine the design specifications and establish design criteria.
Table 6.1 Design process based on DeJonge’s framework Design steps Application to this study 1. Initial Research question request • What are the design criteria for a therapeutic function garment? • What are the physical and psychological needs of pregnant women when wearing maternity support garments? • Which garment characteristics contribute to wearers’ comfort and satisfaction in maternity support garments? 2. Explore Scope of study design • Garment needs of pregnant women direction • Preferences and problems of garment therapy • Mechanistic action of maternity support garment 3. Define Overall aim design goals • To develop a maternity support garment based on the needs of pregnant women (Continued)
115
Table 6.1 (Continued) Design process based on DeJonge’s framework 4. Establish Methods design • Interview to understand the physical and psychological research for needs of pregnant women (Chapter 4) specification • Wear trial to identify the physical sensations when wearing various maternity support garment samples (Chapter 5) • Material tests to determine the physical and mechanical properties e.g. thickness, air permeability (Chapters 6) 5. Establish Results and discussion design • Five main themes of garment needs (Chapter 4) criteria • Attributes of the most comfortable and the least comfortable maternity support garments (Chapter 5) • Objective measurement ranges to be achieved (Chapter 5) • Design criteria (Chapter 6) 6. Prototype Development of garment prototype
development z Based on the design criteria (Chapter 6) 7. Prototype Evaluation of garment prototype
evaluation z By wear trial (Chapter 6)
6.3 Design criteria
Based on the findings from the in-depth individual interviews with the pregnant women, we have generated five main themes of garment needs: a). supportive function, b). comfort, c). ease to put on and take off, d). aesthetics, e). safety. From the wear trials, we identified the attributes of various maternity support garments that influence the wearer’s comfort. Then, we tested the physical and mechanical properties of the materials of the garment samples, so as to determine the preferred fabric characteristics for the new design. Thus, a set of comprehensive design criteria was developed under each main theme of garment needs (Table 6.2). The new design criteria can then be used as the standard on which the evaluation of the prototype is based.
116 Table 6.2 Design criteria and specifications for the new maternity support garments Design criteria Design specifications 1. Supportive functional needs
1.1 Support the lower abdomen • Width of front cradle between 4.5 and 7.5cm (for M size) to encircle the 1.2 Support the lower back lower abdomen • Self-positioned front cradle 1.3 Fit different abdominal and back contours • Adjustable length to fit increasing abdominal size 1.4 Fit well to the lower abdominal crease just • Appropriate pattern above the pubic symphsis 1.5 Fit different postures and increasing • Use of fasteners to allow self-adjusted tension for different activities and abdominal girths with appropriate tension abdominal sizes 1.6 Carry the weight of the abdomen to the • Material with correct extensibility shoulders and upper back with effective • Careful set of grain line of front cradle, side panel, shoulder straps and back pulling force panel that provide correct rigidity • Design the front cradle in such a way that it connects directly to the shoulders and the upper back with the shortest distance for the pulling action • Correct joining position of the shoulder straps to the front cradle
117
Table 6.2 (Continued) Design criteria and specifications for the new maternity support garments Design criteria Design specifications 2. Comfort needs
2.1 Thermal comfort • Thin fabric ≤1.4mm • Light weight ≤ 3.0g/cm2 • Air permeability ≥13.1cc/sec/cm2 2.2 Moisture comfort • Overall moisture management capacity ≥ grade 3 • Cotton or viscose fabric 2.3 Tactile comfort • Soft and smooth fabric without irritating surface • Minimal bulky seams • Flat and smooth stitch types 2.4 Pressure comfort • Stretchable fabric and/or adjustable features to fit the increasing abdominal sizes • Fabric with minimal tension under stretch to prevent excessive pressure on the abdomen • Use of adjustable feature to fit without excessive pressure 2.5 Movement comfort • Same specifications as tactile and pressure comfort
118
Table 6.2 (Continued) Design criteria and specifications for the new maternity support garments
Design criteria Design specifications 3. Convenience needs for putting on and taking off
3.1 Ease to put on garment • Simple style with easy application 3.2 Ease to take off garment • As above 3.3 Ease to remove garment in the toilet • Convenient design for toilet use e.g. cradle or vest 3.4 Ease to apply and adjust fasteners • Simple fastening and adjustable devices
119
Table 6.2 (Continued) Design criteria and specifications for the new maternity support garments
Design criteria Design specifications 4. Aesthetical needs
4.1 Aesthetically pleasing • Simple, pretty or sporty style 4.2 Show nice contour when wearing • Resembles a ‘normal’ underwear e.g. briefs or vest • Stretchable fabric or adjustable feature helps fitting a smooth body contour 4.3 Invisible under outer garment • White, skin or pale colors • Soft fabric with invisible details under outerwear • Smooth seams and minimal bulkiness
120
Table 6.2 (Continued) Design criteria and specifications for the new maternity support garments
Design criteria Design specifications 5. Safety needs
5.1 No excessive pressure over the abdomen • Appropriate uplifting force • Stretchable fabric or adjustable covering for the abdomen to prevent excessive pressure 5.2 No potential danger of tripping and falling • Simple and easy-to-apply design such as cradle or vest when dressing and undressing • No complicated motor coordination involved • No need to balance on one foot or bend forward when putting on or taking off garment
121 6.4 Fabrics tests and selection
Laboratory tests were conducted to determine the physical and mechanical properties of 16 different fabrics. These tests included i) fiber content, ii) fabric structure, iii) density, iv) thickness, v) air permeability, vi) moisture management property, vii) dimensional stability and viii) stretch properties. The fabrics chosen to be tested had to meet the comfort needs as specified in Table 6.2, for example, cotton or viscose material that is thin, absorbent, breathable, soft and smooth in handfeel. Table 6.3 delineates the standard test methods used for testing the fabrics according to the international organizations for textile professionals, American Association of Textile Chemists and Colorists (AATCC) and American Society for Testing and Materials (ASTM).
Air permeability is the measurement of the air flow rate by passing air through the fabric of test area 5cm2 at 100 Pa air pressure difference. The overall moisture management capability (OMMC) is an index to indicate the overall capability of the fabric to manage the transport of liquid moisture, which includes three aspects of performance, the absorption rate, one-way transport capability and spreading rate (Yao et al., 2006). The indices are converted from values to grades based on a five grade scale (5 = Excellent, 4 = Very good, 3 = Good, 2 = Fair, 1 = Poor). The absorption rate is the moisture absorbing time of the fabric’s outer surface. The one-way transport capability is the liquid moisture one-way transfer from the fabric’s inner surface to the outer surface. The spreading rate is the speed of liquid moisture spread on the fabric’s outer surfaces.
Dimensional stability was also tested as it affects the stretch performance and the durability of garment after wash and wear. Fabric stretchability was tested for the selection of materials that meet the requirements of optimal support, fit for better aesthetics, pressure comfort and safety consideration. The force required to extend the fabric used in the supporting panels should be sufficiently large in order to provide good support to the lower abdomen. However, the force needed to stretch the fabric around the abdomen should
122 be minimal to prevent excessive pressure. Figure 6.1 shows the force- deformation curve of a laundered specimen being extended by 100N for 3 cycles.
105 100 95 90 85 80 75 70 65 60 55 50
Force (N) Force 45 40 35 30 25 20 15 10 5 0 0 25 50 75 100 125 150 175 200 225 250 275 300 325
Extension (mm)
Figure 6.1 Three cycles of elongation test on a fabric specimen
For comparison of different fabric specimens, we obtained the force (N) at 20% extension i.e. 25mm (X-axis) during the first of the 3 cycles indicated on the curve. The reason for selecting 20% extension is twofold. Firstly, the maternity support garment is worn between the 2nd and 3rd trimesters. From the subjects’ body measurements, their mean abdominal girth is 93.5cm for the 2nd trimester and 102.1 for the 3rd trimester with the mean abdominal girth enlargement of about 10%. Thus, the fabric needs to be able to stretch at least 10% with minimal force to ensure fitting and comfort for the growing abdomen. Another factor to consider was fit and aesthetics, the fabric used need to be slightly stretched when wearing to cover the whole abdomen in a nice body contour without pleats and wrinkles. Thus, additional 10% elasticity was entailed to stipulate the requirement of 20% extension.
123 Table 6.3 Standard test methods for fabrics Performance Test method Instruments/ Chemicals required Name Number Year i Fiber content Chemical solubility test AATCC 20 2005 75% Sulphuric acid (cotton), 85% Formic acid (nylon), 100% dimethyl formamide (spandex), 10% KOH in ethanol (polyester) ii Fabric structure At a magnification of 200 times - - U-Tex/electro-microscope (Model Ut-901, Japan) iii Density Ratio of the fabric weight to a - - Fabric sample cutter (Model 230/100, James H. Heal and Co. Ltd., UK) fixed unit area (using a circular An electronic balance (Type AY 120, Shimadzu Coorporation, Japan). specimen of 113mm diameter with 100cm2 area) iv Thickness Measure 2mm thick at maximum - - Thickness gauge (Hans Baer AG, CH, Zurich) at pressure 10gms/cm2 Measure 10mm thick at maximum Dial Thickness gauge (Peacock model H, Ozaki MFG. Co. Ltd., Japan) v Air Air permeability of textile fabrics ASTM D737 1996 Air permeability tester (KDG instruments, Sussex, England). permeability vi Moisture According to standard procedure - - Moisture Management Tester (Institute of Clothing and Textiles, PolyU, management for Moisture Management Tester HK) property (MMT) (Yao et al., 2006) vii Dimensional Dimensional changes in automatic AATCC 135 1995 Kenmore heavy duty 70 series washing machine stability home laundering of woven and Kenmore heavy duty plus dryer knit fabrics vii Stretchability Tension and elongation of elastic ASTM D4964 1996 CRE type tensile testing machine (Instron 4411, High Wycombe, UK) fabrics
124 Table 6.4 shows the test results of the material samples in terms of fiber contents, structures, density (g/m2), thickness (mm), air permeability (cc/sec/cm2), dimensional stability (%) and stretchability (Newton). The moisture management property can be presented in terms of average moisture absorption rate (%/sec), one-way liquid transport capacity (%), moisture spreading speed (mm/sec) and overall grade (grade).
Sample 1 was the most preferred maternity support brief in the wear trial as the main fabric contents was cotton. In providing thermophysiological comfort, the favorable fabric had a fabric thickness of 1.4mm, density of 300g/m2, air permeability of 13.1cc/sec, and the overall moisture management capacity of grade 3. It suggests that a good maternity support garment should achieve these minimum requirements in order to provide a satisfactory thermal moisture comfort level for pregnant women as specified in the design criteria (Table 6.2). Therefore, samples 2-7 were chosen for the final garment prototype and the reasons for selection will be discussed in section 6.6.3.
125 Table 6.4 Physical and mechanical properties of tested fabrics Sample number 1 2 3 4 5 (Garment D) Fabric content 70% Cotton 100% Cotton 80% Nylon 90% Nylon 84% Nylon 30% Elastane 20% Spandex 10% Spandex 16% Spandex Enlarged fabric image (Technical front and back)
Fabric structure Weft knit Woven fabric Weft knit Weft knit Warp knit single jersey plain weave single jersey Jacquard satinette Density (g/m2) 300 130 270 260 170 Thickness (mm) 1.4 0.4 0.5 0.5 0.5 Air permeability (cc/sec/cm2) 13.1 35.8 6.6 9.3 >80
Overall Moisture Management Capacity Av. Moisture absorption rate (%/sec) 69.1 82.0 0.0 0.0 0.0 One-way liquid transport capacity (%) 141.3 214.8 -455.7 -441.2 -596.2 Moisture spreading speed (mm/sec) 1.2 1.6 0.0 0.0 0.0 Overall grade 3 4 1 1 1
Dimensional stability (%) - Lengthwise - -8 -1.1 -1.2 0.4 Widthwise - -1.7 -1.0 -1.6 -7.2
Force at 20% extension (N) Lengthwise - Not extensible 4 4 11 Widthwise - Not extensible 4 5 41 Bias direction - 18 3 4 19
(Continued)
126 Table 6.4 (Continued) Physical and mechanical properties of tested fabrics Sample number 6 7 8 9 10 Fabric content 100% Nylon 100% Polyester 100% Cotton 100% Cotton 100% Cotton laminated with polyurethane foam Enlarged fabric image (Technical front and back)
Fabric structure Warp knit Fabric: Weft knit Weft knit Weft knit Weft knit brush tricot single jersey single jersey single jersey single jersey Foam: low density open cell foam Density (g/m2) 170 340 260 150 150 Thickness (mm) 1.1 2.3 1.0 0.5 0.7 Air permeability (cc/sec/cm2) >80 68.6 15.7 >80 52.8
Overall Moisture Management Capacity Av. Moisture absorption rate (%/sec) 338.3 0.0 90.2 97.0 64.0 One-way liquid transport capacity (%) 646.1 -938.9 126.7 86.7 66.2 Moisture spreading speed (mm/sec) 0.02 0.0 1.0 1.0 1.2 Overall grade 4 1 3 3 3
Dimensional stability (%) Lengthwise -0.7 -2.4 -2.4 -8.1 -4.3 Widthwise -0.3 0.1 -2.6 -4.3 -6.5
Force at 20% extension (N) Lengthwise Not extensible Not extensible 5 27 6 Widthwise Not extensible 17 8 8 7 Bias direction Not extensible 22 6 8 6
(Continued)
127 Table 6.4 (Continued) Physical and mechanical properties of tested fabrics Sample number 11 12 13 14 15 Fabric content 100% Cotton 95% Nylon 93% Nylon 86% Nylon 62% Nylon 5% Spandex 7% Spandex 14% Spandex 38% Spandex Enlarged fabric image (Technical front and back)
Fabric structure Net fabric Warp knit Weft knit Warp knit Warp knit tricot weft lock fabric powernet Density (g/m2) 70 220 210 180 230 Thickness (mm) 0.5 0.5 0.6 0.5 0.5 Air permeability (cc/sec/cm2) >80 20.3 11.2 >80 >80
Overall Moisture Management Capacity Av. Moisture absorption rate (%/sec) 61.5 0.0 14.5 17.1 5.1 One-way liquid transport capacity (%) 480.2 -602.1 0.6 -348.0 -494.0 Moisture spreading speed (mm/sec) 1.0 0.0 0.8 0.3 0.02 Overall grade 4 1 1 1 1
Dimensional stability (%) Lengthwise -2.1 -3.1 -6.7 -1.3 -0.9 Widthwise -1.8 -5.5 -1.6 -5.1 -7.1
Force at 20% extension (N) Lengthwise 8 28 2 12 12 Widthwise 2 Not extensible 4 51 13 Bias direction 5 Not extensible 2 29 8
(Continued)
128 Table 6.4 (Continued) Physical and mechanical properties of tested fabrics Sample number 16 17 Fabric content 61% Nylon 20% Nylon 39% Spandex 70% Polyester 10% Spandex Enlarged fabric image (Technical front and back)
Fabric structure Warp knit Weft knit fabric powernet tricot Density (g/m2) 210 160 Thickness (mm) 0.6 0.5 Air permeability (cc/sec/cm2) >80 >80
Overall Moisture Management Capacity Av. Moisture absorption rate (%/sec) 0.0 18.2 One-way liquid transport capacity (%) -617.9 244.5 Moisture spreading speed (mm/sec) 0.0 0.3 Overall grade 1 3
Dimensional stability (%) Lengthwise 0.0 -4.7 Widthwise -3.4 0.3 Force at 20% extension (N) Lengthwise 21 4 Widthwise 13 2 Bias direction 15 3 All the above data are presented as mean. Overall moisture management capacity grade (5 = Excellent, 4 = Very good, 3 = Good, 2 = Fair, 1 = Poor)
129
6.5 Prototype design and development
Based on the design criteria (Table 6.2), the new prototypes were developed from brainstorming design ideas (Figure 6.2), to consolidation of garment design sketches (Figure 6.3) that led to the first physical garment sample (Figures 6.4 and 6.5) produced with technical considerations. During the process of design development, a total of 4 prototype samples were constructed and evaluated. The final prototype (sample 4) was produced for clinical trials on pregnant women with low back pain. Size specifications for the garment prototypes were based on the body measurements of a size 10 Chinese woman during her 26 to 36 weeks of pregnancy, as the maternity support garment is usually worn during the third trimester for therapeutic back pain relief.
The initial design concept was inspired firstly by pregnant women carrying the lower abdomen with both arms (Figure 6.2a) and secondly by the Chinese Dim Sum sales lady in the old days holding a heavy tray with the use of wide straps to carry the anterior load over the shoulders (Figure 6.2b).
A B
Figure 6.2 Garment design concepts
130
Schematic designs
A
B
C
Figure 6.3 Garment design sketches *The arrows represent the resultant forces of the body acting on the garment
131
6.5.1 Style design
When considering the style design for effective support to the abdomen, we considered that the cradle or vest designs would be effective in transferring the fetal weight to the other part of the body (e.g. the shoulders or upper back) other than the lumbar back when compared to the belt or briefs designs. To ensure safety and to facilitate ease to put on, take off, and toilet use, a vest design was preferred because putting on or taking off a vest would not involve lower trunk movement which lessens the danger of falling.
In addition, a vest provides a simple appearance and resembles a normal undergarment. In our first prototype (Figure 6.4), an X-back configuration was designed to create a sporty style look based on Yu & Wong’s (2001) (Yu & Wong, 2001) design (Figure 6.3a), but with improved style design of the side panel, shoulder straps, the back and the adjustable features. Figure 6.5 shows our final prototype which has been refined after several modifications. Details of the modifications will be discussed in the evaluation section 6.7.
As shown in the Figures 6.3 and 6.4, the new design consists of a soft and two-way stretchable front bodice (a) and a one-way stretch U-shaped front cradle (b) encircling the crease of the lower abdomen and joining a pair of wide shoulder straps (c) with plastic fasteners (g). This design ensured effective lifting in the shortest distance from the lower abdomen to the shoulders. The shoulder straps are connected to the back panel (d) at the shoulder blades. The back panel is extended to both sides of the waist. The opening at the side waist is closed by adjustable velcro tape (f) to attach the side panel (e). The length of shoulder straps can also be adjusted using rings and sliders (g). A back belt (h) is a semi-elastic, self-adjustable band, which is attached to the side panel (e) with velcro tapes (f).
132
Figure 6.4 Technical sketch of the first garment prototype
Figure 6.5 Technical sketch of the final garment prototype
133
6.5.2 Pattern design
The developed first pattern is shown in Figure 6.6. The mock garment was initially fitted on a size 10 mannequin to ensure that the straps were in correct positions and that they could fit comfortably on the shoulders and the upper back. Too wide distance between the straps would tend to slip off the shoulders and too narrow distance would cut the neck base and cause neck pain. After the initial fitting test and pattern adaption on the mannequin, the first prototype was made to fit a live model in her gestational week 28. This fitting was examined in a wear test involving specified movements such as sitting and walking. The five main themes of garment needs had been met and several unmet needs have guided the revisions to the prototype pattern.
134
Figure 6.6 Pattern shape of the first prototype *The arrows represent the grain lines of the fabrics; S.A. = Seam allowance All the edges have seam allowance of 7mm unless indicated otherwise
135 In the first prototype, the back panel was formed by 2 layers of cotton woven fabric in straight grain (Figure 6.7a), which joins the upper ends of the shoulder straps. The straight grain in both layers results in creases in the X-configuration as indicated by the grey arrows (Figure 6.7.a) because of the fabric is stretchable in the bias direction (Sample 2 in Table 6.4) leading to insufficient strength to support the anterior load.
After careful consideration, the grain line of the inner layer (Figure 6.7b) of back panel was modified to bias cut in order to provide rigidity to the back panel as indicated by the grey arrows (Figure 6.7b) since the cotton woven fabric used is not extensible in lengthwise and widthwise (Sample 2 in Table 6.4), while the outer layer remained straight cut to allow slight fabric stretch in the bias direction for movement comfort. Figure 6.8 shows the pattern shape of the final prototype.
A B
Figure 6.7 Grain lines of the back panel
136
Figure 6.8 Pattern shape of the final prototype *The arrows represent the grain lines of the fabrics; S.A. = Seam allowance All the edges have seam allowance of 7mm unless indicated otherwise
137
6.5.3 Details of each component and the materials used in the final prototype
The final prototype was developed with careful considerations of the stitch types and seam construction. Table 6.5 shows the seam diagrams with indication of number of fabric layers and the materials used for each component. The corresponding number in the earlier table 6.4 is also given for reference.
Table 6.5 The layers, materials and seam constructions Component No. of Materials used Sample no. layers in Table 6.4 a Front bodice 1 80% nylon 20% spandex or 3/4 90% nylon 10% spandex b Front cradle 3 I: 100% cotton woven 2 M: 100% polyester laminated 7 with polyurethane foam O: 84% nylon 16% spandex 5 warp knit satinette c Shoulder 3 100% cotton woven 2 strap d Back panel 2 100% cotton woven 2
e Side panel 3 I: 100% cotton woven 2 M: 100% polyester laminated 7 with polyurethane foam O: 100% nylon brush tricot 6 h Back belt 3 Same as front cradle Same as front (Both ends made of 2 layers of cradle 84% nylon 16% spandex warp knit satinette) I = Inner layer; M = Middle layer; O = Outer layer
138
a) Front bodice
This elastic fabric covers most part of the enlarged abdomen and serves various functions: i) to accommodate and fit the increasing abdominal sizes, ii) to prevent excessive pressure, iii) to provide a vest-like appearance, iv) to generate a warm and smooth handfeel. The front bodice should be a two- way stretchable material so we used one layer of single jersey or Jacquard Nylon fabric (Samples 3/4 in Table 6.4). It is a soft and smooth fabric with good handfeel for tactile comfort. The fabric was thin (0.5mm), light (260- 270 g/m2), and has good dimensional stability (≤-1.6%) and great stretchability (≤5N at 30% extension) providing minimal tension around the abdomen and a smooth abdominal contour. The other stretchable fabrics (Samples 13 and 17 in Table 6.4) also had similar physical and mechanical properties except for their less desirable dimensional stability (≥-4.7%). Overstretched fabrics form wrinkles which will affect the fit and aesthetic appearance. b) Front cradle
Careful consideration was required in the width of the cradle. Too narrow a cradle lacks sufficient support and a too wide one leads to fabric creases causing discomfort and bulkiness. Good fitting cradle should consist of 4.5cm wide fabric panel designed to fit the body crease of the lower abdomen. It was composed of 3 layers of different fabrics (Table 6.5). The next-to-skin layer is a thin (0.4mm) and breathable (air permeability = 35.8cc/sec/cm2) 100% cotton fabric (Sample 2 in Table 6.4) for thermophysiological comfort. The middle layer was a laminated polyurethane foam sheet (Sample 7 in Table 6.4) Although the foam did not meet the heat and moisture transfer requirements; it was still selected for several reasons. Firstly, it provides a cushioning effect for better pressure comfort. Secondly, it helped to form the shape of a cradle to facilitate ease to wear. Thirdly, it only covers a small area of the body (the lower and both
139 sides of the abdomen). The outer layer was covered with a thin one-way stretch 16% spandex 84% nylon material (Sample 5 in Table 6.4) which gave rigidity in the widthwise direction (41N at 30% extension) and stretchability in the lengthwise (11N at 30% extension). Samples 12, 14 and 16 were also suitable fabrics to provide good support. However, Sample 12 was too rigid to touch, and the colors of the samples 14 (brown color) and 16 (pale blue) matched the design criteria but not the color scheme (white) of the final prototype. c) Shoulder straps
A light weight (density = 130g/m2) cotton woven fabric (Sample 2 in Table 6.4) was chosen for the shoulder straps because it is non-elastic and strong enough to provide a sturdy and firm support to the abdomen and back with inherent heat and moisture transfer properties (OMMC = 4). The challenge encountered was that using a thin fabric to promote thermo-moisture comfort, may not have sufficient tensile strength to bear the increasing fetal weight. The other cotton fabrics (Samples 8-11 in Table 6.4) were not suitable mainly because of unsatisfactory tension (≤10N at 30% stretch). Therefore, the shoulder straps used enclosed seam construction to form a 3- layer cotton woven fabric to provide a lifting up for the weight of the growing abdomen over the shoulders.
One dilemma when designing the force distribution feature was that the transferred load to the shoulders may help to relieve lower back pain but on the other hand it may cause shoulder pain. Therefore, to avoid excessive pressure on the shoulders, the shoulder straps were designed to be wider (3.6cm) than the usual vest undergarment. However, the wider straps may conflict with aesthetics appearance as they might be visible under the outer garment. To fit the increasing abdominal sizes, the lengths of the shoulder straps were made to be adjustable.
140 d) Back panel
The back panel is an X-shaped configuration with 2 layers of cotton (Sample 2 in Table 6.4). A bias grain inner layer was sewn onto a straight grain outer layer with enclosed seam to reinforce the strength of the back panel. The upper ends are connected to the shoulder straps and the lower ends extend and conform to the back body contour and attach with velcro on the side panels. The X-shaped configuration was used to reduce the amount of fabric covering the back to further promote thermophysiological comfort. e) Side panel
The side panel is a 13cm wide extension from the front cradle. The upper end forms a loop for direct attachment to the shoulder straps. This design aimed to directly transfer some of the fetal weight to the shoulders and upper back. The outer layer of brush tricot fabric was used for attachment of velcro tapes. This allowed self-adjusted position to fit different waist heights and to accommodate the increasing abdominal sizes. The middle and inner layers of fabrication were the same as the front cradle. f) Velcro tape
Adjustable features should be used to promote good fitting for optimal support and better comfort without compressing the abdomen. For the closure, selecting an appropriate fastener was a challenge in that a firmly secured fastening device is usually made from a relatively hard material such as plastic or metal which causes discomfort as it presses against the abdomen. On the other hand, a soft and flexible fastening device is more comfortable however it can be easily detached considering the weight it has to bear.
141 Velcro tape was selected for the closure at side seam because it was useful for quick application, readjustment and removal. It was also conveniently positioned at the waist for the ease to put on and take off. The velcro tape chosen had a soft and non-scratchy surface, which is ideal for the sensitive skin of pregnant women. We used velcro tape partnered with brush tricot fabric (Sample 6 in Table 6.4) to promote fitting and to avoid excessive compression to the abdomen. g) Plastic fasteners
The garment closure must be durable and strong enough to withstand the amount of weight, yet it tended to be large and bulky which created a conflict with the aesthetic design. A rectangular shaped ring is used to attach the loops of the side panels to the shoulder straps. A set of ring and slider was selected as it is a simple and adjustable device as the mechanism of which is similar to that of bra straps. h) Back belt
The back belt is a 5.5cm wide band designed to fit around the waist to reinforce back support and to prevent the garment from riding up. The belt is made from 3 layers of different fabrics which are very similar to that of the front cradle (Table 6.5). Slight modification was made to both ends of the belt as described in the evaluation section 6.7. The 2 layers of one way stretch satinette fabric at the ends allowed a small amount of stretch to provide a firm support as well as pressure comfort during changing of postures.
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6.5.4 Seam and stitch types
For the majority of the plain seams, enclosed seams and top stitching, we used single-needle lock stitch to provide a flat and strong sewing construction. All the raw edges of the front bodice, and side panels were covered with fold-over elastic binding that formed smooth and elastic seams for better body conforming. Cover-stitches were used to provide a flat and smooth surface, which minimized skin irritation during movement.
6.6 Evaluation of prototype
The evaluation of the prototype is the final step of the DeJonge functional design process, but it was in effect an ongoing process throughout the development of the garment prototype. The prototypes were evaluated in the wear tests on another size 10 pregnant subject from gestational week 26 to 36. Table 6.6 shows the amendments made from prototype sample 1 through sample 4. Detailed descriptions of the comments from the model and fitting experts are given in the section 6.7.1.
143 Table 6.6 A close-up of the amendments made in samples 1 to 4 Change Sample 1 Sample 2 i
ii
iii
144
Table 6.6 (Continued) A close-up of the amendments made in samples 1 to 4 Change Sample 2 Sample 3 iv
v
vi
145
Table 6.6 (Continued) A close-up of the amendments made in samples 1 to 4 Change Sample 3 Sample 4 vii
viii
ix
x
Black ring and slider White ring and slider
146 The prototypes were evaluated against the five main themes of garment needs and design criteria including a) supportive function, b) comfort, c) ease to put on and take off, d) aesthetics, and e) safety. Prototype revisions were made based on the feedback from the subject and the opinions of the fitting experts. Comments were also encouraged from the manufacturer regarding production difficulties.
The final evaluation required the model to wear the garment prototype for one week. Once she confirmed that the garment met the design criteria as outlined in Table 6.2, the pattern set was sent to a local manufacturer for the production of 40 garments (Figure 6.9) for clinical trial evaluation. The results of the clinical trials will be reported in Chapter 7.
Front view Side view Back view
Left oblique views Figure 6.9 The final garment prototype for clinical trials
147
6.6.1 Clothing and textiles experts’ opinions a) Supportive function
The experts observed that the fabric of the upper back panels had wrinkles and seemed to be less supportive than potentially possible. To improve the supporting system, the grain line of the inner layer was changed to bias (Table 6.6i) to fit the back of the body better and the outer layer remained using a straight grain for the support of the abdominal weight. Several modifications were made to improve the velcro attachment. Firstly, the side panel was enlarged (Table 6.6ii) and the top fabric was changed to a brush tricot fabric (Table 6.6v) for a larger area of velcro attachment. Sewing several rows of velcro tapes was problematic as the edges were easily broken after dense stitching causing it prickling to touch. Single stitching lines (Table 6.6v) were used instead of multiple stitching lines. This not only stabilized the inner layers but also for a better adhesiveness.
To further improve the supportive function, the stitch lines on the side panels were modified from horizontal to vertical (Table 6.6viii) for a stronger adhesive effect of the velcro. The brush tricot fabric was extended to an additional 5cm on each side (Table 6.6viii) to allow for extensible length of the back belt so as to fit the various abdominal girths. Further modification was made to the shoulder straps by adding the seam allowance in all enclosed seam to form a 3 cotton layers (Table 6.6ix and Table 6.5c) for better strength. b) Comfort
The experts felt that zigzag stitches on the inner surface of the cradle was a little rough to touch which may become a concern for skin irritation, so changes were made to use cover stitches (Table 6.6iii) and nylon fuzzy thread on the inner side and polyester thread on the outer side. For better tactile and thermo-moisture comfort, cotton fabric lining was added onto the
148 cradle (Table 6.6iii). To further improve the thermo-moisture comfort, the thickness of back belt was reduced by 10cm by eliminating the form layer on each end (Table 6.6 vii). The remaining two layers were made from the elastic fabric (Table 6.6 vii) which provided a slight degree of stretchability and better comfort during different postures such as from standing to sitting.
For pressure comfort, the standard of comfort pressure is 10-20mmHg (or 500g fabric stretch) for close fitting garments as commercial products. In our study, the main focus is on the biomechanics, physical and psychological needs, and aesthetic preference of pregnant women. Although the garment pressure was not measured in this study, the wearers have assessed it by subjective testing, which may even be more accurate than the pressure sensors since pregnant women have increased skin sensitivity and individual preference for garment pressure.
c) Aesthetics
For a better appearance, the experts modified the square corners of the back belt to oval corners (Table 6.6vii) and a set of less bulky ring and slider (Table 6.6x) was used for the final prototype to minimize bulkiness. Matching white colored fasteners replaced the black colored ones (Table 6.6x).
No further revisions were necessary in both aspects of safety and ease to put on and take off.
6.6.2 Subject’s feedback a) Supportive function
The subject felt that the lower abdomen was sufficiently supported and that some of the load was transmitted onto her shoulders and upper back. However, the subject complained about the riding up of the garment.
149 Therefore, a back belt (Table 6.6iv) was constructed for attachment onto the side panel to provide some pressure on the back as a reinforcement to hold to garment in place as well as to support wearer’s lumbar back. An adjustable belt was designed to fit the increasing abdominal sizes. The back belt provided adequate back support and prevented the riding up of the garment. b) Comfort
The prototype was comfortable to wear and generally allowed freedom of movement. The subject commented that during walking, the movements of her arms sometimes caught the edges of the buckle fasteners which may hinder normal comfortable arm swings. The buckle fasteners were therefore replaced with 20mm medium-sized rectangular shaped rings (Table 6.6vi) as they had a less bulky design but able to withstand the tension of the shoulder straps. c) Ease to put on and take off
The subject thought that the vest design with a cradle made it easy to visualize how it should be worn. The adjustable features were conveniently positioned which facilitated application and readjustment for different positions. Taking off the prototype was relatively convenient because the detachable velcro fastenings allowed easy removal. For putting on the garment, bending her arms backwards to find the attachment arm of the velcro was slightly awkward. Improvement was made by increasing the area of side panels (Table 6.6ii) which allowed for a larger opening which facilitates putting on the garment without detaching the velcro. d) Safety
Safety concern was not raised throughout the subject’s evaluation. The design of a vest only involved upper trunk therefore there was no concern of
150 tripping or falling over. The subject did not feel excessive pressure over the abdomen since both the abdominal and back panels were easily adjusted. e) Aesthetics
The subject commented that the prototype looked good as a functional maternity vest. Fit was the main concern for the subject. Loose fitting of the abdominal front panel made the subject felt uneasy but gathers were added to the upper region of the abdominal panel (Table 6.6iii) to improve the fitting.
6.6.3 Manufacturing challenges
The manufacturer has encountered several sewing problems. The design of the side panel was changed from a round corner to a pointed angle (Table 6.6ii) to facilitate sewing at a turning angle. Another sewing problem was related to the velcro tape since the edges became brittle and abrasive with dense stitches. The stitches were therefore modified to double stitches covered with a 29D tricot tape binders (Table 6.6ii). The back belt consisting of oval corners with the fold-over elastic was difficult to sew, therefore was changed to square corners (Table 6.6vii).
A Made to Measure approach was adopted in the processes of development and evaluation of this maternity support garment prototype. To achieve mass production of maternity support garments as commercial products, the experience of our pilot study suggests that different body heights, abdominal shapes and sizes would need to be carefully analyzed in order to develop the appropriate size range for the target wearers.
6.7 Conclusion
The DeJonge’s functional design model provided a conceptual framework for the design, development and evaluation of maternity support garment. It facilitated the process of identifying the problems and exploring the design
151 situation from an objective and comprehensive perspective. Through identification of the five main themes of garment needs including supportive function, comfort, ease to put on and take off, aesthetics and safety, the most and least comfortable garment features, and the material tests of physical and mechanical properties; the key design criteria were formulated and garment prototypes were designed and developed. The garment prototypes were evaluated by a live pregnant model together with fitting experts. The results showed that the new garment prototype has achieved the requirements of the design criteria for maternity support garments. Future studies are also needed to establish guidelines for achieving safe in terms of optimal pressure; and effective support garment therapy for the relief of low back pain during pregnancy.
Data presented in this chapter will be presented in a journal manuscript to be submitted to Ergonomics (to be submitted in September 2008).
152 CHAPTER 7
CLINICAL TRIAL OF MATERNITY SUPPORT VEST FOR
PREGNANCY-RELATED LOW BACK PAIN: A PILOT STUDY
7.1 Introduction
This chapter presents a pilot clinical study of the maternity support vest prototype in the evaluative phase of this study. The original goal was to assess the effectiveness of the garment prototype as an adjunct therapy to the conventional exercises with scientific evidence preferably in a randomized controlled trial (RCT). However, due to insufficient number of subjects, this study was changed to a feasibility trial for the future RCT study. Therefore, the objectives of this pilot study was to investigate the feasibility of the maternity support vest for the relief of pregnancy-related low back pain, to assess any adverse effect in long term wearing of this new vest prototype, and to reveal limitations in the design of the proposed clinical trial.
7.2 Methods
7.2.1 Study design
This was a pilot clinical study to examine the effect of maternity support vest prototype as an adjunct therapy to the conventional treatment (intervention group) compared with conventional treatment (control group) in women with PBLP (Figure 7.1).
153
Figure 7.1 Study design
7.2.2 Study population
The study was conducted in the antenatal clinic of a local university hospital. Ethical approval was sought from the Hospital Authority and the University. Participation was on a voluntary basis. All subjects gave written informed consent. A study sample of pregnant women was recruited according to the following selection criteria.
The inclusion criteria are:
i. The subjects are able to communicate fluently in Cantonese, ii. The subjects should be Hong Kong Chinese women carrying a singleton pregnancy, iii. Primigravida (pregnant for the first time) at gestational week 28, iv. Had experienced PLBP,
154 The exclusion criteria are: i. Previous spinal surgery, structural damage or gross structural defect of the spine ii. A history of chronic LBP or LBP due to specific underlying pathology such as infection, tumor, osteoporosis, rheumatoid arthritis, fracture, inflammation, or musculoskeletal disease
The subjects were randomized using the predetermined list. Each subject had an equal chance of being allocated to the intervention or the control group. Figure 7.2 shows a summary of recruitment, randomization, loss to follow and assessment. Of 86 women recruited for the initial screening, 65 women did not meet the selection criteria and 7 women did not follow the exercises program. After exclusion of ineligible subjects, 14 women met our eligibility and were randomly allocated into two arms of our study - 5 women in the intervention group and 9 women in the control group. Five women were lost to follow up (4 women attended private hospitals for delivery and 1 had early delivery due to uterine problem). Therefore, 9 women were included in the final data analysis. All subjects accepted the designated treatment and none of them requested for the alternate treatment group.
155
Figure 7.2 Summary of recruitment, randomization, and loss to follow
Blinding is preferred in intervention studies as it may lessen the influences of human preference or expectation regarding the effectiveness of intervention (Halpern, 2003). While blinding of garment treatment is not feasible, all subjects were asked to first state their perceived effectiveness of maternity support garments before they were allocated to the treatment. This was done to see whether the perceived effectiveness would influence the outcome. The patients were blind to the pre-treatment assessment. The researcher also assessed the post-treatment pain intensity and functional status without referring to the pre-treatment assessment. To reduce the Hawthorne effect, whereby patients in the intervention group receive more attention, the researcher was not allowed to contact both groups apart from the time of pre-treatment and post- treatment assessment.
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7.2.3 Interventions
Each subject received 7 weeks of treatment for PLBP from week 29 to week 36 of pregnancy. The control group participated in an antenatal exercises training program offered by the physiotherapist. The intervention group received the same exercises training as the control group, but in addition, they were asked to wear a maternity support vest. The maternity support garment is recommended to be worn during the daytime particularly when prolonged standing and walking were anticipated. Each subject in the intervention group was given two prototypes of maternity support vests so she can continue to wear a clean support garment everyday. Both groups were encouraged to perform antenatal exercises for PLBP at home.
7.2.4 Outcome measurements
Each subject was approached for five times for different assessments (Table 7.1), first at the baseline (i.e. gestational week 29), then in weeks 1, 3, and 7 after the women received intervention, and lastly followed in the postnatal week 4. At baseline, each subject was asked to provide demographic data and clinical history (Appendix 11). Data on the intervention feasibility and comfort evaluation were collected at the completion of the intervention. Other assessments included pain measures, biomechanical measures and pregnancy outcomes are described below. At the completion of 7 weeks treatment, co-treatment, compliance to exercises, heavy physical work and psychosocial stress factors were also documented since these factors may confound the results.
7.2.6.1 Intervention feasibility and comfort evaluation
The feasibility of garment treatment was revealed by the responses in the overall satisfaction and acceptance of the garment prototype, the wearing compliance and subject retention rates. Wear comfort is one of the most important factors that influence wearing compliance. Therefore, the subjects
157 were also asked to rate the key comfort factors using the magnitude scaling method as described in Chapter 5. They included overall comfort, abdominal comfort, ease to wear, aesthetic design, heat transfer and freedom of movement. To better understand the factors associated with comfort and feasibility of garment therapy, the subjects were asked in an open-ended format to report on any other discomforts or problems that would hinder them from wearing the maternity support vest.
7.2.6.2 Pain measures
There were two primary outcome measures for pain including pain intensity and functional status. Pain intensity was measured by the Numeric Rating Scale (NRS) (Grotle et al., 2005; Ostelo et al., 2005) to assess the average intensity of pain experienced at present and in the past week. Functional status was assessed using the Roland-Morris Disability Questionnaire (RMDQ) (Grotle et al., 2004; Roland & Morris, 1983) to determine the influence of pain on various levels of daily activities on the day of assessment. Detailed descriptions of NRS and RMDQ including the methods of assessment were presented in Chapter 3. In the week 7 post- treatment, the global improvement of pain symptoms was assessed using a 5-point Likert scale (1=much worse, 2=slightly worse, 3=unchanged, 4=slightly improved, and 5=much improved) (Breen & Breen, 2003).
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Table 7.1 The timeline for outcome measures assessment Assessment Baseline Week 1 Week 4 Week 7 Follow up (Gestational (week 30) (week 33) (week 36) (postpartum week 29) week 4) Demographic & clinical data X Intervention feasibility and comfort evaluation Comfort factors X Acceptance and satisfaction X Compliance and subject X retention rate Pain measures Pain intensity (NRS) – X X X X Present & Past week Functional status (RMDQ) X X X X Global improvement X Biomechanical measures BW X AG X X SAD X X COP X X SLC X X Pregnancy outcomes Week at delivery X Mode of delivery X Birth weight X APGAR score X Obstetric complications X NRS = Numeric Rating Scale, RMDQ = Roland-Morris Disability Questionnaire, BW = Body weight, AG = abdominal girth, SAD = Sagittal abdominal depth, COP = Centre of pressure, SLC = Sagittal lumbar curve
159 7.2.6.3 Biomechanical measures
To observe the trends of the biomechanical measures of COP and SLC in the two groups to see whether there is any immediate and long term effects of wearing the maternity support vest on postural change. The immediate effect (COPG) was determined by examining the COP with and without the vest in a random order among the intervention group. BW, AG and SAD were also measured. Detailed descriptions of the outcome measurements and the instruments used were presented in Chapter 3.
7.2.6.4 Pregnancy outcomes
Pregnancy outcomes were examined to check if there were any possible adverse effects of pain intervention on LBP among pregnant women (Kvorning et al., 2004). Therefore, during the follow up assessment after delivery, pregnancy outcomes were obtained in this study. They included the week and mode of delivery, birth weight, Apgar score, and obstetric complications, if any. The Apgar score is the routine method of evaluating the physical condition of a newborn infant shortly after delivery. It is a number resulted from scoring the heart rate, respiratory effort, muscle tone, skin color, and response to a catheter in the nostril. Each of these clinical signs receives 0, 1, or 2 points. The highest Apgar score of 10 means an infant is in the best possible condition. An infant with an Apgar score of less than 4 needs immediate resuscitation. The Apgar score is done routinely at 60 seconds after the birth of infant and then again 5 minutes after birth. In the event that resuscitation is required for prolonged period, the Apgar score may be assessed again at 10, 15, and 20 minutes after delivery.
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7.2.5 Procedure
Pregnant women were approached while they were awaiting their antenatal examination at the clinic. Subjects who do not meet the selection criteria did not enter into the study. Written informed consents were obtained after providing explanation of the aims and procedure of the intervention study. Subjects were randomly allocated into one of the two groups (intervention group and control group). For the intervention group, standard instructions regarding the appropriate positioning of the abdominal band, pressure to be applied, the proper use of special adjustable features, and laundry instructions, were given.
Figure 7.3 outlines the procedure for this pilot study. During every assessment, the subjects in both groups were encouraged to perform the exercises taught by the physiotherapist in the antenatal class. To reduce the possible confounding effect of attention, the researcher did not spend additional time or interaction with the patient, other than that for the standardized assessment procedures.
161
Explanation (written and oral) given Consent form signed Demographic questionnaire and pain measures
assessment completed
The subject changed into a hospital gown
Abdominal girth measured by measuring tape Sagittal abdominal depth measured by a Martin large sliding caliper
Sagittal lumbar curve measured by the spinal gauge
Centre of pressure measured by the centre of pressure platform
Figure 7.3 The procedure for the pilot study
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7.2.6 Data analysis
All analyses were performed using SPSS for Windows version 14.0 (SPSS Inc., Chicago, IL). All variables are presented as mean values with standard deviations. Comparisons of continuous and categorical variables between the treatment groups were performed by the Student t tests and Fisher’s exact tests correspondingly.
7.3 Results
Table 7.2 shows that the baseline characteristics including the demographic and clinical data were similar in the intervention and the control groups. None of the subjects were using any co-treatment during the intervention period except one in the control group was wearing a maternity support belt (commercial product). When the subjects were asked to rate the perceived effectiveness of maternity support garments (1 = Effective, 2 = Not effective, 3 = Don’t know), one subject from each group perceived it as effective and the remaining were uncertain whether the maternity support garments were effective.
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Table 7.2 Demographic and clinical characteristics of the subjects in the intervention and control groups (n = 9) Characteristic Intervention Control P-value Group Group (n = 4) (n = 5) Age (years) 32.8 (3.1) 34.0 (3.2) NS (0.571) Body height (cm) 160.0 (4.8) 158.2 (4.6) NS (0.692) Body weight (kg) (normal) 55.8 (3.5) 53.2 (8.2) NS (0.579) Baseline 29.3 (0.5) 28.4 (1.1) NS (0.212) Week 1 30.3 (0.5) 29.4 (1.1) NS (0.212) Week 3 33.3 (0.5) 32.4 (1.1) NS (0.212) Week 7 35.8 (1.0) 36.2 (1.8) NS (0.666) PLBP (0-10 points) Onset (weeks) 20.0 (10.4) 16.2 (9.4) NS (0.608) NRS (at onset) 3.0 (1.4) 3.4 (2.0) NS (0.742) NRS - Present (baseline) 2 (2.2) 0.8 (0.8) NS (0.286) NRS - Past week (baseline) 2.5 (0.6) 2.4 (2.1) NS (0.922) RMDQ (0-24 points) 7.3 (4.3) 8.2 (3.3) NS (0.716) Full time work (%) 4 (100.0) 5 (100.0) NS (1.000) Regular exercises before 3 (33.3) 4 (44.4) NS (0.722) pregnancy (%)
Heavy physical work (%) 1 (11.1) 0 (0.0) NS (0.444) Psychosocial stress (%) 0 (0.0) 1 (11.1) NS (0.556) Co-treatment (%) 0 (0.0) 1 (11.1) NS (0.556) Data are presented as mean (SD) or number (%). *P<0.05, NS = not significant. NRS = Numeric Rating Scale; RMDQ = Roland-Morris Disability Questionnaire
164 7.3.1 Overall acceptance and satisfaction, compliance and retention rates, and comfort evaluation
Regarding intervention feasibility, the subjects reported high levels of satisfaction and acceptance. The majority gave either 9/10 or 8/10 for the maternity support vest. The rate of subject retention was high. As noted, 4 out of 5 subjects enrolled to wear the maternity support garments completed the study. One subject did not complete the study due to obstetric reason. Their adherence to wearing the maternity support vest further supported the intervention’s feasibility. Three out four women wore the maternity support vest for an average of 5 times/week, 9 hours/day for 7 weeks. This was considered a high wearing compliance, since all the women felt that they only needed to wear it during weekdays in the work places. Only one woman did not totally comply with the garment therapy, and she wore the vest for 2 times/week, 10 hours/day for 4 weeks. The exercise’s compliance rate was similar in both groups. The control group performed 28 (S.D. 17.5) minutes/week, and the intervention group did 33.8 (S.D. 26.9) minutes/week.
Figure 7.4 presents the comfort responses in the maternity support vest in comparison to the results of the optimal garment (Garment D) in our wear trials of Chapter 4. Among the nine factors assessed, seven of them received a higher score in the maternity support vest than Garment D. The heat transfer property of the maternity support vest had a lower score (6.5 ± 2.8) because 75% of the women felt excessive heat over the back panel. One woman expressed concern that the wide shoulder straps might be visible when wearing an outerwear with wide neck opening. Although the data are not directly comparable (Figure 7.4), it provides a general indication that the maternity support vest was superior to the Garment D. Future wear trials are needed to confirm the results. No other discomforts or problems were reported relating to the use of the maternity support vest such as shoulder ache, excessive pressure around the abdomen, or inconvenience of adjustment.
165
7.3.2 Pain11 intensity, functional status and global improvement 10 9
8 7 6
5 4 3 2 1 0
t s rt gn fer o si nt omf de trans tchines isfaction l comfor c ic t -i at ea on Acceptance S Mean(SD) comfort score (0: worst, 10:best) Ease to wearsthet H N Overal Ae Abdominal Freedom of moveme
Maternity support t Garment D
Figure 7.4 Comfort evaluation scores of maternity support vest and Garment D
7.3.2 Pain intensity, functional status and global improvement
When examining the present pain intensity, figure 7.5 shows that the control group had progressive increase in pain intensity (0.8 ± 0.8 to 2.8 ± 2.7) whereas the intervention group was more effective in reducing pain intensity but only more notable at week 4 (2.0 ± 2.2 to 0.5 ± 1.0). This pain reduction was accompanied by a little improvement in the functional status as reflected by a slight decrease in RMDQ scores (7.3 ± 4.3 to 5.0 ± 7.4) (Figure 7.5). While the past week pain intensity in the intervention group was similar (2.3 ± 1.7 to 2.5 ± 1.9) throughout the intervention period, the control group had less pain at week 1 (1.8 ± 0.8) but the pain seemed to gradually worsen (3.4 ± 2.4) near the time of delivery, and also affected their functional status (7.2 ± 3.3) (Figure 7.5).
166 10 Intervention group (present) 9 Control group (present) 8 Intervention group (past week) Comtrol group (past week) 7 6 5 4 3 Pain intensity (NRS) 2 1 0
24 22 Intervention group 20 Control group 18 16 14 12 10
RMDQ scores 8 6 4 2 0 Baseline Week 1 Week 4 Week 7
Figure 7.5 Mean (SD) of pain intensity and Roland-Morris Disability Questionnaire scores between the intervention and control groups
167 Three of the four women in the intervention group rated much improvement after wearing the garment in combination with the exercises (Figure 7.6). Conversely, 3 of the 5 women in the control group reported no change or even slightly worse after performing exercises alone.
Much improved 3/4
Slightly improved 2/5
No change 2/5 1/4
Slightly worse 1/5
control Intervention Much worse
Figure 7.6 Percentage of global improvement
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7.3.3 Biomechanical measures
The means (S.D.) of the biomechanical measures of the intervention and control groups are presented in Table 7.3. At the baseline, the tested biomechanical measures were similar between the treatment groups except for COP and SLC. It is therefore not possible to compare the COP and SLC data of the two groups. In addition, due to the small samples in this pilot study, no rigorous statistical tests were conducted to examine the differences in COP and SLC between the two groups. As seen in Table 7.3, a slight posterior shift in the COP was only noted at week 7 (from 36.9 ± 7.7 to 34.0 ± 4.5). The immediate COP response at week 1 (from 35.9 ± 3.8 to 36.5 ± 3.4) or long term COP response (from 35.9 ± 3.8 to 36.9 ± 7.7) were not observed.
Table 7.3 Biomechanical data of the intervention and control groups at baseline and week 7 (n = 9) Baseline Week 7 Intervention Control (n=5) Intervention Control (n=5) (n=4) (n=4) BW (kg) 63.9 (4.3) 62.6 (10.3) AG (cm) 97.0 (3.9) 96.8 (6.5) 100.3 (2.8) 104.8 (8.3) SAD (cm) 27.9 (1.5) 27.8 (2.4) 29.3 (1.0) 31.0 (3.4) COPN (mm) 35.9 (3.8) 39.5 (10.0) 36.9 (7.7) 35.6 (11.4) COPG (mm) 36.5 (3.4) - 34.0 (4.5) - SLC (º) 46.3 (13.4) 40.4 (4.6) 42.0 (12.6) 46.0 (9.5)
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7.3.4 Pregnancy outcomes
Table 7.4 showed that both groups had term pregnancy and an Apgar score above 8.0 at 10 minutes. No adverse effects were reported in women who wore the vest prototype.
Table 7.4 Pregnancy outcomes of the intervention and control groups (n =8) Characteristic Intervention Group Control Group (n = 4) (n = 4)† Delivery Week 37.8 (0.5) 38.0 (0.8) NSD (%) 2 (25.0) 1 (12.5) CS (%) 2 (25.0) 3 (37.5) Fetus Body weight (kg) 3.1 (0.2) 2.8 (0.3) Apgar score at 0 minute 8.3 (1.5) 7.5 (3.7) Apgar score at 10 minutes 9.3 (1.0) 8.5 (3.0) Complications (%) 0 (0.0) 1 (11.1) Data are presented as mean (SD) unless stated otherwise. NS = not significant. NSD = Normal spontaneous delivery; CS = Caesarean section; † = 1 missing data
7.4 Discussion
The maternity support vest was both feasible and comfortable to wear as a combined treatment for pregnancy-related low back pain. The high scores (7.5 or above) in the comfort factors, acceptance and satisfaction of the garment indicate that the garment prototype is well accepted and feasible for use in future trials. In this study, a high total compliance (3 out of 4) was achieved for the newly developed maternity support vest, which was much better than a previous study examining the compliance rate of pressure
170 garment for burns patients that showed only 41% of total compliance (Johnson et al., 1994). Although the number of subjects was few, the retention rate was high. The reason for the one subject who discontinued the intervention was related to reasons other than the garment.
The difficulty encountered in recruitment of subjects should be addressed. One of the main reasons for the limited sample size is the operation and nature of the research venue. The university antenatal clinic only runs morning sessions twice a week. This reduces substantially the number of available subjects to be approached in limited time and resources. Secondly, the clinic is partly intended for seeing women who had undergone in-vitro fertilization (IVF) which usually leads to twin or multiple pregnancies. This further decreases the number of recruitable subjects due to the stringent selection criteria in this study. It is suggested that multicentre recruitment in future trials would increase the sample size and generalizability of the results.
Long term wearing of maternity support vest as an adjunct to exercises training seemed to have some beneficial effects over exercises alone for pregnant women with low back pain. However, it is important to note that the mean pain intensity (1-3) of both groups was at mild level. This low intensity of pain is not a critical level compared to moderate pain intensity of 5-6, which would have substantially more interference with the daily functions (Serlin et al., 1995). Future studies should target at inclusion of subjects with pain intensity of at least 5 (moderate level) to generate more meaningful data of a quantifiable range of adequate pain relief. In addition, a crossover design is necessary to differentiate the effect of time on pain.
The perception of global improvement in this study is unlikely to be attributed to a psychological effect emerging between the women and the researcher because both groups received the same amount of time of interaction. It may be explained that wearing a support garment may foster an increased sense of protection and security. Additional studies are necessary to delineate these possible effects with the inclusion of a placebo
171 treatment in future randomized controlled trials. Given that most subjects (80%) did not have preconceived views about efficacy of the maternity support vests, the garments were effective even in patients who were not highly motivated. Due to the small sample size, the generalizability of the results of this study is limited. However, it is possible that a larger study would reveal more significant discernable results.
No apparent immediate or long term effects of maternity support vest were found on the centre of pressure, the effect of which was expected to be in a posterior direction. This is based on the assumption that as the anterior load is embraced by the garment closer to the body, the moment arm would be a lesser distance, and in turn the flexion moment imposed on the spine would be reduced, the equation for the calculation of which was already described in Chapter 3. It must be noted, however, that the lack of posterior shifting in the COP did not necessarily indicate the absence of effect. Most likely, the effects on the subjects were not large enough to be detected. It is also possible that there are other more important biomechanical factors in explaining pain reduction. The long term wearing of maternity support vest did not have any adverse effect on the pregnancy outcomes.
7.5 Conclusion
This pilot clinical study suggests that the maternity support vest is feasible, comfortable, safe, and has promising effects on pregnancy-related low back pain. However, the garment prototype needs to be further developed in order to improve the heat transfer over the back panel and the aesthetics concern in the shoulder straps. Due to the small sample of subjects, the results cannot be generalized. Future randomized controlled trial should be a crossover design including a placebo arm with a larger sample size to distinguish the psychophysical and biomechanical effects. Both findings of high compliance rate and garment evaluation scores provide evidence that the newly established design criteria are useful guides in developing therapeutic functional garments.
172
Data presented in this chapter will be submitted to Journal of Clinical Nursing (to be submitted in September 2008).
173 CHAPTER 8
CONCLUSIONS
8.1 The research problems
LBP during pregnancy is highly prevalent. The pain symptoms often recur or become chronic, which impact significantly on women’s quality of life and the healthcare resources. Many pregnant women suffering from PLBP and/or PPP often wear maternity support garments for pain relief as they are widely advocated and easily accessible. The patients and healthcare professionals have reported that the existing maternity support garments were unsatisfactory, yet the pregnant women’s requirements of garment treatment in both functional and comfort terms are not clear. Furthermore, there is a lack of knowledge regarding the efficacy, health effect, and mechanistic action of these therapeutic functional garments. All these factors affect the treatment compliance, and ultimately the treatment effect.
8.2 Research aims and methods
The overall aim of this study was to develop the design criteria and prototypes of maternity support garments based on the biomechanical changes during pregnancy, the physical and psychological needs of pregnant women and their comfort responses when wearing these garments. To investigate these, three exploratory studies (biomechanical study, in-depth interviews, wear trials) and laboratory tests were conducted. The DeJonge’s functional design model was employed as the conceptual framework to develop the design criteria, and to design, develop, and evaluate the garment prototypes. After the final garment prototype was developed, we evaluated the feasibility and comfort of the prototype, beneficial and adverse effects of garment therapy using a pilot clinical trial.
174
8.3 Highlights of research findings
The longitudinal biomechanical study (Chapter 3) quantified that the effect of pregnancy on the anterior centre of pressure projectories together with the centre of pressure compensation. The compensatory response to postural instability did not seem to involve the lumbar curvature. Corresponding posterior centre of pressure shift to counteract the anterior shifting of centre of pressure was only evident from the 1st to 2nd trimester of pregnancy. These findings enhanced the understanding in the theories of LBP during pregnancy regarding postural strategies. Out of the six biomechanical variables, centre of pressure and sagittal lumbar curvature were selected to be the objective measures to evaluate how the garment therapy influences postural alteration.
The semi-structured interviews (Chapter 4) elicited the pregnant women’s personal views with real samples of maternity support garments to stimulate responses. Five main themes of garment needs were found. They included the effectiveness of function, safety, comfort, ease to put on and take off, and aesthetics. The findings revealed that the maternity garment design and fabrication requires special attention to the physiological and psychological changes of pregnant women in order to achieve both the functional and aesthetical values. This study also showed that most interviewees have worn the maternity support belts for back support and back discomfort, but all except one have discontinued wearing it due to various garment-related problems such as excessive hotness, perceived ineffectiveness, itchiness, excessive tightness, and inconvenience in adjustment.
The wear trials (Chapter 5) evaluated the wearers’ comfort responses on maternity support garment samples. The subjective comfort responses (Chapter 5) showed that the perceived thermal and moisture comfort was largely influenced by the fiber contents, breathability, and moisture transfer properties which are normally related to the thickness, density, and porosity influenced by the fabric knitting construction. The material properties of
175 stretch, handfeel and garment tension all contributed to tactile comfort, while the garment type and style features affect the comfort in movement. Movement comfort was influenced by the garment type and style features.
It was revealed that one of the maternity support briefs (Garment D) was perceived as the best product among the tested garments in terms of thermal, moisture, sensorial, and movement comfort. According to the results of the material tests, the optimal garment consisted of a thin (1.4mm), lightweight (300g/m2), and breathable (air permeability of 13.1cc/sec) fabric with high cotton fiber content (70%) and the overall moisture management capacity was grade 3. In addition, it was soft and smooth in handfeel, and invisible and highly stretchable in fitting, which allowed easy movements and convenience for toileting. These findings suggest that a good maternity support garment should achieve these minimum requirements in order to provide a satisfactory wear comfort level for pregnant women. On the contrary, the maternity support cradle (Garment G) was the most disliked because it was clumsy to wear and the material was rigid and non- breathable. It also had poor hand feel and moisture transfer. The relatively stiff and nonadjustable abdominal band tended to cause discomfort by localizing pressure over the abdomen and the elastic bands over the torso made the wearer felt “tied up” and difficult to put on and take off.
After consolidating the new knowledge and research data from the systematic in-depth interviews, the wear trials and material tests, a set of comprehensive design criteria was formulated (Chapter 6). Five design criteria constituted the five main themes of garment needs including supportive function, comfort, ease to put on and take off, aesthetics, and safety. Four samples of garment prototypes were developed and evaluated based on the new design criteria by two live pregnant models and two fitting experts.
The pilot clinical study (Chapter 7) showed a high total compliance rate (3 out of 4 women wore the vest prototype for 5 times/week; 9 hours/day for 7weeks). It was found that the vest prototype is feasible and comfortable to
176 wear, and seems promising as an adjunct therapy to exercises for the relief of pregnancy-related low back pain in future clinical trials. Long term wearing of the vest prototype did not have any major adverse effects on the maternal or fetal health. These findings indicate that the new design criteria were useful in guiding the design and development of the maternity support garments and will serve as groundwork for future refinement work.
8.4 Significance and contribution of the study
The popular use of maternity support garments, in conjunction with a lack of research evidence in the efficacy and health effect, the high prevalence of LBP among pregnant women, and the need for an easily accessible and non- pharmaceutical mean of pain relief, form the context and highlight the importance of this study. The originality in the research topic and methodologies will contribute to the theoretical understanding of design and development of therapeutic garments. The research deliverables contribute by providing an important step forward in the scientific development and evaluation of garment therapy.
8.5 Limitations of the study and future research
Based on the resources available in terms of manpower and facilities, there were some limitations in this study. Overall, the study is limited to a small sample of Asian women. Future investigation should include a larger sample size of women from different countries and climates, which will help to refine the design criteria and specifications of maternity support garments for different markets.
In the interviews and wear trials, 8 garment samples available in Hong Kong were purposefully selected to elicit the pregnant women’s responses. Future research into more garment samples in both subjective and objective evaluation would improve the specification of the best fabric for individual type of comfort needs.
177 The scope of the biomechanical study was limited to the analysis of 6 important biomechanical changes of pregnant women. More studies are required to identify the critical biomechanical factor that is associated with pregnancy-related low back pain. Future work may study the 3D body changes, the resultant kinetics of increasing anterior load and its effect on spinal loading. Biomechanical models can be developed for the garment design with prediction of kinetic force requirements. It will also be interesting to study how the force magnitude and direction are influenced by different garment types, style designs, fabrics, and pattern, as well as the grading methods for different sizes.
During the developmental phase of garment prototyping, the physical and mechanical properties of 16 different fabrics were considered. Future work can select more materials for laboratory tests so as to further enhance the quality of garment prototypes. These specified fabric requirements will be beneficial to the future design, development and testing of functional garments. Although the pilot clinical study showed promising results of global improvement of pain and high compliance with garment therapy, the psychophysical effect of garment wearing has not been distinguished. Such effect may be differentiated in future randomized controlled trials using the commercially-available products as the placebo.
178
Appendix 1
INFORMATION SHEET
Maternity Garment Treatment for the Relief of Low Back Pain (Biomechanical study)
You are invited to participate in a study conducted by the Institute of Textiles and Clothing of The Hong Kong Polytechnic University. This study aims to examine the anthropometry and the biomechanics of the pregnant women during the third trimester of their pregnancy. Based on the created knowledge, new principles will be used for the functional design and evaluation of maternity foundation garment for the relief of low back pain for pregnant women. First, we will use a spinal gauge to capture your spinal contours. Then, we will measure your centre of pressure and body weight using a COP Platform. The above procedures will take approximately 30 minutes and will be repeated in subsequent follow-ups at weeks 28 and 36 of pregnancy.
All information related to you will remain confidential, and will be identifiable by codes only known to the researcher. All data collected will be used solely for this study. You have every right to withdraw from the study before or during the research without penalty of any kind. If you have any complaints about the conduct of this research study, please do not hesitate to contact Mr. Eric Chan, Secretary of the Human Subjects Ethics Sub-Committee of The Hong Kong Polytechnic University in person or in writing (c/o Human Resources Office of the University). If you would like more information about this study, please contact Dr. Winnie Yu at telephone number 2766-6525.
It is hoped that the research deliverables not only help to relieve the problems of low back pain, but also have a large impact to alert people about the health concerns in designing garments for special needs.
Thank you for your interest in participating in this study.
Dr. Winnie Yu Principal Investigator / Chief Investigator
179 Appendix 2
有 關 資 料 可減輕懷孕女性腰背痛的孕婦服裝治療 （生物力學研究）
你好，我們謹代表香港理工大學紡織及製衣學系誠邀你參與一項研究計劃。這項 研究的目的在於探索在妊娠末期的孕婦的人體測量學及生物力學的特點。這些有 關生物力學的特點的新的知識及理論，可用以功能設計及評估可減輕懷孕女性腰 背痛的孕婦服裝。首先，我們會利用一個測量的工具找出你腹部及背部的輪廓。 然後再用中央壓力平台量度你的中央壓力及體重。這些程序約需 30 分鐘，並會 在懷孕的第 24 及第 36 星期再重覆一次。
所有有關你的個人資料將會被保密處理，並會被編成只有研究人員才能理解的編 碼保存，而所得的數據也只會作研究用途。你有絕對的權利在研究開始前或進行 時要求退出，退出研究後你絕不會受到任何懲罰。如果閣下對這項研究有任何投 訴或意見，歡迎以書面或親身與香港理工大學人事倫理委員會秘書陳先生聯絡 （請郵寄至以下地址轉交：香港理工大學人力資源辦公室）。如果閣下希望獲得 更多有關這項研究計劃的資料，歡迎於辦公時間內與余詠文博士（電話：2766 6525）聯絡。
我們希望這項研究不單能幫助減輕懷孕女性腰背痛，更能喚起人們在設計有特別 需要的服裝時對健康的關注。人體測量學及生物力學的數據分析亦會為家居及復 康產品設計方面，特別在設計不常見體型及結構的產品時帶來貢獻。 多謝閣下的參與！ 余詠文博士 研究主管／首席研究員
180 Appendix 3
INFORMATION SHEET
Maternity Garment Treatment for the Relief of Low Back Pain (Semi-structured interview)
You are invited to participate in a study conducted by the Institute of Textiles and Clothing of The Hong Kong Polytechnic University. This study aims to examine the psychological needs of pregnant women who have suffered from low back pain during their pregnancy. Based on the created knowledge, new principles will be used for the functional design and evaluation of maternity support garment for the relief of low back pain for pregnant women. You will participate in an interview to explore your experience of low back pain during pregnancy, your views and feelings towards maternity garment, and your perception in the cause and relief of low back pain. The interview time will be approximately 1 hour.
All information related to you will remain confidential, and will be identifiable by codes only known to the researcher. All data collected will be used solely for this study. You have every right to withdraw from the study before or during the research without penalty of any kind. If you have any complaints about the conduct of this research study, please do not hesitate to contact Mr. Eric Chan, Secretary of the Human Subjects Ethics Sub-Committee of The Hong Kong Polytechnic University in person or in writing (c/o Human Resources Office of the University). If you would like more information about this study, please contact Dr. Winnie Yu at telephone number 2766-6525.
It is hoped that the research deliverables not only help to relieve the problems of low back pain, but also have a large impact to alert people about the health concerns in designing garments for special needs.
Thank you for your interest in participating in this study.
Dr. Winnie Yu Principal Investigator / Chief Investigator
181 Appendix 4
有 關 資 料 可減輕懷孕女性腰背痛的孕婦服裝治療 （面談）
你好，我們謹代表香港理工大學紡織及製衣學系誠邀你參與一項研究 計劃。這項研究的目的在於探索患有腰背痛的懷孕女性的心理需要的 特點。這些有關心理特點的新的知識及理論，可用以功能設計及評估 可減輕懷腰背痛的孕婦服裝。你會獲邀參加一個面談，以探討你對懷 孕時腰背痛的體驗及成因的見解，以及你對孕婦服裝的意見及感覺。 這項研究大約需一小時。
所有有關你的個人資料將會被保密處理，並只有研究人員才能理解的 編碼保存，而所得的數據也只會作研究用途。你有絕對的權利在研究 開始前或進行時要求退出，退出研究後你絕不會受到任何懲罰。如果 閣下對這項研究有任何投訴或意見，歡迎以書面或親身與香港理工大 學人事倫理委員會秘書陳先生聯絡 (請郵寄至以下地址轉交：香港理工 大學人力資源辦公室）。如果閣下希望獲得更多有關這項研究計劃的 資料，歡迎於辦公時間內與余詠文博士（電話:2766 6525）聯絡。
我們希望這項研究不單能幫助減輕懷孕女性腰背痛，更能喚起人們在 設計有特別需要的服裝時對健康的關注。
多謝閣下的參與！
余詠文博士 研究主管／首席研究員
182 Appendix 5
INFORMATION SHEET
Maternity Garment Treatment for the Relief of Low Back Pain (Wear Trial)
You are invited to participate in a study conducted by the Institute of Textiles and Clothing of The Hong Kong Polytechnic University. This study aims to evaluate some commercially available maternity garments. You will participate in a trial wearing of different types of maternity garment and you are asked to provide your opinion and your score on a scale regarding the quality and acceptability of the garments. The data collection time will be approximately 1 hour.
All information related to you will remain confidential, and will be identifiable by codes only known to the researcher. All data collected will be used solely for this study. You have every right to withdraw from the study before or during the research without penalty of any kind. If you have any complaints about the conduct of this research study, please do not hesitate to contact Mr. Eric Chan, Secretary of the Human Subjects Ethics Sub-Committee of The Hong Kong Polytechnic University in person or in writing (c/o Human Resources Office of the University). If you would like more information about this study, please contact Dr. Winnie Yu at telephone number 2766-6525.
It is hoped that the research deliverables not only to help relief the problems of low back pain, but also have a large impact to alert people about the health concerns in designing garments for special needs.
Thank you for your interest in participating in this study.
Dr. Winnie Yu Principal Investigator / Chief Investigator
183 Appendix 6
有 關 資 料 可減輕懷孕女性腰背痛的孕婦服裝治療 （試穿計劃）
你好，我們謹代表香港理工大學紡織及製衣學系誠邀你參與一項研究計劃。 這項研究的目的在於評估一些可買到的孕婦服裝。你會被邀請參加一項試穿 計劃，試穿不同種類的孕婦服裝，同時你需在一份評級問卷上寫出你對該服 裝的品質的意見及可接受程度。這項研究大約需一小時。
所有有關你的個人資料將會被保密處理，並只有研究人員才能理解的編碼保 存，而所得的數據也只會作研究用途。你有絕對的權利在研究開始前或進行 時要求退出，退出研究後你絕不會受到任何懲罰。如果閣下對這項研究有任 何投訴或意見，歡迎以書面或親身與香港理工大學人事倫理委員會秘書陳先 生聯絡（請郵寄至以下地址轉交：香港理工大學人力資源辦公室）。如果閣 下希望獲得更多有關這項研究計劃的資料，歡迎於辦公時間內與余詠文博士 （電話：2766 6525）聯絡。
我們希望這項研究能幫助減輕孕婦腰背痛，更能喚起人們在設計有特別需要 的服裝時對健康的關注。
多謝閣下的參與！
余詠文博士 研究主管／首席研究員
184 Appendix 7
INFORMATION SHEET
Maternity Garment Treatment for the Relief of Low Back Pain (Clinical trial)
You are invited to participate in a study conducted by the Institute of Textiles and Clothing in The Hong Kong Polytechnic University. This study aims to examine the effectiveness of the maternity support garment in relief of low back pain for pregnant women in their 3rd trimester. First, you will be randomly allocated into an intervention group (wearing maternity support garment + exercises) or a control group (exercises only), and then you are requested to wear the maternity garment for 8 weeks. Assessments will be made before, during and after the clinical trial to measure your pain and biomechanical parameters on weeks 28, 29, 32, 36 of pregnancy and postpartum week 4.
All information related to you will remain confidential, and will be identifiable by codes only known to the researcher. All data collected will be used solely for this study. You have every right to withdraw from the study before or during the research without penalty of any kind. If you have any complaints about the conduct of this research study, please do not hesitate to contact Mr. Eric Chan, Secretary of the Human Subjects Ethics Sub-Committee of The Hong Kong Polytechnic University in person or in writing (c/o Human Resources Office of the University). If you would like more information about this study, please contact Dr. Winnie Yu at telephone number 2766-6525.
It is hoped that the research deliverables not only help to prevent the problems of low back pain, but also have a large impact to alert people about the health concerns in designing garments for special needs.
Thank you for your interest in participating in this study.
Dr. Winnie Yu Principal Investigator / Chief Investigator
185 Appendix 8
有 關 資 料 可減輕懷孕女性腰背痛的孕婦服裝治療 (臨床實驗)
你好，我們謹代表香港理工大學紡織及製衣學系誠邀你參與一項研究計劃。 這項研究的目的在於測試孕婦支撐服裝對減輕已懷孕九個月的孕婦的腰背痛 的功效。首先，你會被隨機編進介入組（穿著孕婦服裝 + 運動）或對照組 （運動）。你需要穿著這套孕婦服裝 8 星期。在研究測試前，進行中及完成 後，我們會進行量度，包括在第 28, 29, 32, 36 懷孕週及產後第 4 週，量度 你的疼痛及生物力學指數。
所有有關你的個人資料將會被保密處理，並會被編成只有研究人員才能理解 的編碼保存，而所得的數據也只會作研究用途。你有絕對的權利在研究開始 前或進行時要求退出，退出研究後你絕不會受到任何懲罰。如果閣下對這項 研究有任何投訴或意見，歡迎以書面或親身與香港理工大學人事倫理委員會 秘書陳先生聯絡（請郵寄至以下地址轉交：香港理工大學人力資源辦公 室）。如果閣下希望獲得更多有關這項研究計劃的資料，歡迎於辦公時間內 與余詠文博士（電話：2766 6525）聯絡。
我們希望這項研究不單能幫助減輕懷孕女性腰背痛，更能喚起人們在設計有 特別需要的服裝時對健康的關注。 多謝閣下的參與！
余詠文博士 研究主管／首席研究員
186 Appendix 9
CONSENT TO PARTICIPATE IN RESEARCH
Maternity Garment Treatment for the Relief of Low Back Pain
I ______hereby consent to participate in the captioned research conducted by the Institute of Textiles and Clothing, The Hong Kong Polytechnic University.
I understand that information obtained from this research may be used in future research and published. However, my right to privacy will be retained, i.e. my personal details will not be revealed.
The procedure as set out in the attached information sheet has been fully explained. I understand the benefit and risks involved. My participation in the project is voluntary.
I acknowledge that I have the right to question any part of the procedure and can withdraw from the study at any time without penalty of any kind.
Name of participant
Signature of participant
Name of researcher
Signature of researcher
Date
187
Appendix 11
Demographic Data Questionnaire
1. Age： 2. Height： cm
3a. Weight (before pregnancy) : Kg/lb 3b. Weight （now）: Kg/lb
4. Occupation： ☐ Housewife ☐ Others：
5. Do you have any spinal disease or had spinal surgery？ ☐ Yes ☐ No If so, please state：
6a. Have you ever smoked？ ☐ Yes ☐ No （If the answer is no, go to question 7a）
6b. Are you currently smoking？ ☐ Yes ☐ No
6c. How many cigarettes are you smoking per day？ 6d. Smoked for : years
6e. Quitted for： years
7a. Have you ever used oral ☐ Yes ☐ No（If the answer is no, go to 7b. Duration： years contraceptives？ question 8）
8. How many pregnancies have you had？ （If the answer is 1, go to question 12a） （including this one）
9. Have you experienced LBP during and/or after your ☐ Yes ☐ No previous pregnancy？
10. Have you ever had epidural anesthesia? ☐ Yes ☐ No
11. Have you ever had caesarean section？ ☐ Yes ☐ No
12a. Have you ever experienced LBP? (does not include LBP related to this pregnancy) ☐ Yes ☐ No
12b. If so, when was the most recent episode? Months/years ago
13. Your present gestational week：
14 Have you experienced LBP during this pregnancy ☐ Yes ☐ No
15a. Have you used the maternity support garment (e.g. belt) to help in the ☐ Yes ☐ No If so, please relief of your back pain? state：
15b. If you have back pain now, would you accept maternity support garment as a ☐ Yes ☐ No treatment to relieve your back pain？ § If you have experienced LBP during this pregnancy, please CONTINUE with the following questions. If you have not experienced LBP during this pregnancy, tick ‘no’ in question 16a and this is the end of the questionnaire. THANK YOU.
189
16. Are you taking any analgesics？ ☐ Yes ☐ No If so, please state：
17a. LBP started at week: of pregnancy
17b. Peak pain intensity at week: of pregnancy
17c. Location of pain： On the diagram below, mark an ‘X’ on the area that you feel pain in your back
17d. Radiation of pain: ☐ Yes ☐ No If yes, mark “O” in the area that the pain radiates to on the same diagram
17e. Nature of LBP: (Describe how your pain feels like, e.g. dull, sharp, aching, muscle pulling, numbness, tingling, burning, electrical shock sensation). Please circle one or more of the descriptions or write in the space below.
17f. Nature of radiation pain: (Describe how it feels in the area where the pain radiates to e.g. dull, sharp, aching, muscle pulling, numbness, tingling, burning, electrical shock sensation). Please circle one or more of the descriptions or write in the space below
18. Did you take time off from work because of your ☐ Ye ☐ No If so, how long? days back pain? s
19. Did you seek medical help for your pregnancy associated ☐ Ye ☐ No back pain？ s
20. Have you received any ☐ Physiotherap ☐ Others, please treatments for LBP y state:
Thank you for your time and participation！
190 Appendix 12
個人資料問題
1. 年齡： 歲 2. 身高： 厘米
3a. 體重（懷孕前）: 千克 3b. 體重 （現在）: 千克
4. 職業： ☐ 家庭主婦 ☐ 其他：
5. 你有否患任何脊骨的疾病 (例如脊背變形，或肌肉筋骨 ☐ 有 ☐ 沒有 如有，請註明： 的疾病)，或曾經接受脊背手術？
6a. 你曾經有吸煙嗎？ ☐ 有 ☐ 沒有（如沒有，請跳至第 7a 題）
6b. 你現在有吸煙嗎？ ☐ 有 ☐ 沒有（如沒有，請跳至第 6e 題）
6c. 你每天平均吸多少支香煙？ 支 6d. 已吸煙 : 年 (請跳至第 7a 題）
6e. 已戒煙： 年
7a. 你曾否服食避孕藥嗎？ ☐ 有 ☐ 沒有（如沒有，請跳至第 8 題） 7b. 已服食： 年
8. 你曾經懷孕多少次？（包括這一次） 次（如果這是你第一次懷孕，請跳至第 12 題）
9. 在你過往懷孕時，有否曾經感到腰背痛？ ☐ 有 ☐ 沒有
10. 你有否曾經接受無痛分娩 ? ☐ 有 ☐ 沒有
11. 你有否曾經剖腹生產？ ☐ 有 ☐ 沒有
12a. 在懷孕之前，你曾否有腰背痛嗎？ ☐ 有 ☐ 沒有
12b. 如果有，最近一次是什麼時候出現? 個月/年前
13. 你現在懷孕多少週?： 妊娠週
14 在今次懷孕時有否出現腰背痛？ ☐ 有 ☐ 沒有
15a. 你有否曾經穿著妊娠服裝 (例如托腹帶/褲)來幫助你減輕腰背痛？ ☐ 有 ☐ 沒有 如有，請 註明：
15b. 如果你有腰背痛，你會接受及依從減輕腰背痛的妊娠服裝治療嗎？ ☐ 會 ☐ 不會
§ 如果在今次懷孕中你有腰背痛，請完成以下問題。如在第 15a 題選擇「沒有」，問卷在此完結，多謝參與！
191
16. 你現在有否服食止痛的藥物？ ☐ 有 ☐ 沒有 如有，請註明：
17a. 腰背痛在那一妊娠週出現？ 妊娠週
17b. 腰背痛的最高峰在那個妊娠週出現？ 妊娠週
17c. 腰背疼痛的位置： 在下面的圖樣中，請在你背部出現疼痛的位置上畫上“X”◦
17d. 反射性疼痛 (指除了腰背痛以外，疼痛有時會轉射在身體的其他位置) ☐ 有 ☐ 沒有 (如有，請在上面的圖樣中畫上 “O”代表反射性疼痛的位置)
17e. 腰背痛的感覺： (圈出一個或多個形容疼痛的用詞或在空位中寫上其他疼痛的感覺。例如隱隱作痛、明 顯尖銳的疼痛、持續地痛、肌肉拉扯、麻木感覺、刺痛、像火灼地痛、像電擊地痛)。
17f. 反射性疼痛的感覺： (圈出一個或多個形容疼痛的用詞或在空位中寫上其他的感覺。例如隱隱作痛、明顯尖 銳的疼痛、持續地痛、肌肉拉扯、麻木感覺、刺痛、像火灼地痛、像電擊地痛）。
18. 你有沒有因為今次懷孕時腰背痛而需要請假休息？ ☐ 有 ☐ 沒有 如有，總共多少日?： 日
19. 你有沒有曾經因為今次懷孕時腰背痛而看醫生？ ☐ 有 ☐ 沒有 如沒有，請跳至第 16 題
20. 曾接受甚麼治療？ ☐ 物理治療 ☐ 其他，請註明：
多謝你寶貴的時間及參與！
192 Appendix 13
Numeric Rating Scale a) English version b) Chinese version
a) English version
Write down the single number that best represents your level of pain intensity. Average pain intensity: ______Peak pain intensity: ______
0 1 2 3 4 5 6 7 8 9 10 No pain Worst pain imaginable
b) Chinese version
疼痛程度表
請填上 0 至 10 其中一個數字以代表你的平均疼痛程度: ___ 最高峰疼痛程度: ___
0 1 2 3 4 5 6 7 8 9 10
沒有疼痛 你能想像的最痛
193 Appendix 14
The Roland–Morris Disability Questionnaire
When your back hurts, you may find it difficult to do some things you normally do.
This list contains sentences that people have used to describe themselves when they have back pain. When you read them, you may find that some stand out because they describe you today. As you read the list, think of yourself today. When you read a sentence that describes you today, put a tick against it. If the sentence does not describe you, then leave the space blank and go on to the next one. Remember, only tick the sentence if you are sure it describes you today.
□ 1. I stay at home most of the time because of my back. □ 2. I change position frequently to try and get my back comfortable. □ 3. I walk more slowly than usual because of my back. □ 4. Because of my back I am not doing any of the jobs that I usually do around the house. □ 5. Because of my back, I use a handrail to get upstairs. □ 6. Because of my back, I lie down to rest more often. □ 7. Because of my back, I have to hold on to something to get out of an easy chair. □ 8. Because of my back, I try to get other people to do things for me. □ 9. I get dressed more slowly then usual because of my back. □ 10. I only stand for short periods of time because of my back. □ 11. Because of my back, I try not to bend or kneel down. □ 12. I find it difficult to get out of a chair because of my back. □ 13. My back is painful almost all the time. □ 14. I find it difficult to turn over in bed because of my back. □ 15. My appetite is not very good because of my back pain. □ 16. I have trouble putting on my socks (or stockings) because of the pain in my back. □ 17. I only walk short distances because of my back. □ 18. I sleep less well on my back. □ 19. Because of my back pain, I get dressed with help from someone else. □ 20. I sit down for most of the day because of my back. □ 21. I avoid heavy jobs around the house because of my back. □ 22. Because of my back pain, I am more irritable and bad tempered with people than usual. □ 23. Because of my back, I go upstairs more slowly than usual. □ 24. I stay in bed most of the time because of my back.
194 Appendix 15
Roland–Morris 生活能力程度問卷
當你的腰背痛時，你會發現一些平時能輕易做到的事情會變得困難◦
以下列表中的句子是一些有腰背痛的人用以形容自己。當你細閱它們的時 候，你可能覺得有些句子也能形容你現時的情況。當你閱讀句子時，想一想 你現在的情況，如果你發現有句子能形容你現在的狀況，請在旁邊的格子中 填上“√”。如果句子不能應用在你身上，請留空格子跳至下一句。請緊 記，當你肯定那句子能形容你現在的狀況時才填上“√”。
1. 因為我的背痛，我時常逗留在家中◦ ☐ 2. 我時常轉換位置以嘗試令我背部舒服一點◦ ☐ 3. 因為我的背痛，我走路比平時慢了很多◦ ☐ 4. 因為我的背痛，我不做平時在家中常做的事◦ ☐ 5. 因為我的背痛，我上樓梯時要使用扶手◦ ☐ 6. 因為我的背痛，我時常躺下來休息◦ ☐ 7. 因為我的背痛，我需要扶著東西才能從椅子中站起來◦ ☐ 8. 因為我的背痛，我做事時需要別人的幫忙◦ ☐ 9. 因為我的背痛，我穿衣比平時慢了很多◦ ☐ 10. 因為我的背痛，我只可以站立短時間◦ ☐ 11. 因為我的背痛，我盡量不會彎身或跪下◦ ☐ 12. 因為我的背痛，我覺了在椅子中站起來時有困難◦ ☐ 13. 我的背部幾乎時時也痛楚◦ ☐ 14. 因為我的背痛，我覺得在床上轉身時有困難◦ ☐ 15. 因為我的背痛，我的胃口不太好◦ ☐ 16. 因為我的背痛，我要很辛苦才能穿上襪子◦ ☐ 17. 因為我的背痛，我只能走很短的路程◦ ☐ 18. 因為我的背痛，我睡得不好◦ ☐ 19. 因為我的背痛，我穿衣時需要別人幫忙◦ ☐ 20. 因為我的背痛，我幾乎整日都坐下來◦ ☐ 21. 因為我的背痛，我避免做家中的粗重工作◦ ☐ 22. 因為我的背痛，我比平時容易發怒及脾氣暴躁◦ ☐ 23. 因為我的背痛，我上樓梯時比平慢很多◦ ☐ 24. 因為我的背痛，我大多數的時間卧在床上◦ ☐
195 Appendix 16 Interview guide
I. Problems related to pregnancy and pregnancy-related LBP 1. What is the one thing that you worry the most during pregnancy? 2. What is your emotion/mood like on a typical day since your pregnancy? 3. Do you think the above psychological factors that you have just mentioned would affect your LBP during pregnancy? 4. Tell me about your LBP experience. 5. What do you perceive as the cause of your LBP during pregnancy? 6. Can you think of any factors that aggravate or reduce your LBP?
II. Comments on Commercially Available Product 1. Have you used any maternity support garment? 2. Why did you (not) use it? 3. What type of garment have you used? 4. When do you usually wear the garment? 5. Do you find the garment help in reducing LBP during pregnancy? 6. How do you think the garment work to reduce LBP during pregnancy? 7. What are the merits and drawbacks of the garments that you have used? 8. Take a good look at these garment samples (A-H) one by one and tell me what you like/dislike about each garment and give your reasons 9. From these samples, choose one garment that your think is the best/ worst and give reasons for your choice.
III. Suggestions for New Product 1. What styles/designs do you prefer and why? 2. Which colour do you prefer and why? 3. What kind of materials do you prefer and why? 4. What type of accessories do you prefer and why? 5. Here is a diagram (below) showing some of the important factors for the design of a new maternity support garment, which do you think are the top five important ones and rank them from the order of the most important to the least important. You can add factors that are not on this diagram.
freedom of movement color (easy to mix and match)
comfort design material handfeel
not itchy ease to put on and take off
not leaving a mark on the skin
aesthetic appearance heat transfer moisture transfer
196 Appendix 17 Wear Trial Evaluation Questionnaire
Wearer Code : Date of Trial :
First, write down (in the blank) two numbers that represent your “best” and “worst” scores (the numbers can be positive or negative numeral). Best score = ______, worst score = ______. Then, for each assessment item listed below, please indicate a score (inside the brackets) that best describes the maternity garment or how you feel about the garment that you are wearing. This score must be between your best and worst scores.
Garment codes A B C D E F G H I. Product outlook Order of wearing [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 1. Design [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. Material [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. Handfeel [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. Color [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 5. Others: [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] II. Sensations when wearing 1. Ease to put on [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. Appearance (looks good) [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. Garment invisible [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] underclothing 4. Heat transfer [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 5. Moisture absorbability [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 6. Others: [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] III. Comfort sensations during body movements 1. Standing to sitting [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. Sitting to standing [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. Walking [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. Bend over then stand up [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] straight 5. Crouch then stand up straight [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 6. Twist waist [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 7. Freedom of movement [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 8. Lower back [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 9. Abdomen [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 10. Overall comfort [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 11. Others： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] IV. Sensations when undressing 1. Ease to take off [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. Ease to release and refasten [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] after using the toilet 3. Feels itchy [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. Not leaving a mark on the skin [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 11. others： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] V. Overall performance 1. Overall acceptance [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. Overall satisfaction [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
197 Appendix 18 試穿評估問卷
首先，選擇及寫出（在空位內）一個數字以代表你的「最佳」分數，然後再選擇一個數字以代表你的 「最差」分數（這些數字可以是正數或負數）。你的最佳分數是 (＿＿) ，你的最差分數是 (＿＿) 。然 後，請就以下列表中每一項評估項目，指出一個可以最適合形容妊娠服裝及你對你現時穿著的服裝的感 覺的分數。這個分數必須介乎你的最佳及最差分數之間。
試穿種類編號 A B C D E F G H I. 產品外型 試穿次序 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 1. 設計 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. 質料 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. 手感 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. 顏色 (容易配襯衣服) [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 5. 其他： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] II. 穿著時的感覺 1. 容易穿上 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. 穿著後的外觀 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. 穿著外衣後不容易被察覺 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. 熱力散發程度 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 5. 濕氣吸收力 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 6. 其他： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] III. 身體移動時舒適的感覺 1. 由站立到坐下 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. 由坐下到站立 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. 步行 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. 彎腰再挺直身子 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 5. 蹲下再站起來 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 6. 扭腰 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 7. 移動時的自由度 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 8. 下背部 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 9. 腹部 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 10. 感覺舒適 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 11. 其他： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] IV. 穿著後的感覺 1. 容易脫下 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. 用洗手間時, 容易放鬆及繫緊 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 3. 不會感覺痕癢 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 4. 不會在皮膚上留下印記 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 11. 其他： [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] V. 總體表現 1. 總體可接受程度 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ] 2. 總體滿意程度 [ ] [ ] [ ] [ ] [ ] [ ] [ ] [ ]
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