Pregnancy-Related Pelvic Girdle Pain and Its Relationship with Relaxin Levels During Pregnancy: a Systematic Review
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Eur Spine J DOI 10.1007/s00586-012-2162-x REVIEW ARTICLE Pregnancy-related pelvic girdle pain and its relationship with relaxin levels during pregnancy: a systematic review Daniela Aldabe • Daniel Cury Ribeiro • Stephan Milosavljevic • Melanie Dawn Bussey Received: 13 September 2011 / Revised: 11 January 2012 / Accepted: 18 January 2012 Ó Springer-Verlag 2012 Abstract Conclusions Based on these findings, the level of evi- Purpose The present systematic review assessed the level of dence for the association between PPGP and relaxin levels evidence for the association between relaxin levels and preg- was found to be low. PPGP assessment and controlling for nancy-related pelvic girdle pain (PPGP) during pregnancy. risk factors were found to increase bias leaving uncertainty Methods PRISMA guidelines were followed to conduct in interpretation of these findings and a need for further this systematic review. Electronic search was carried out research. using six different databases. Observational cohorts, cross- sectional or case–control studies focused on the association Keywords Pregnancy-related pelvic girdle pain Á between relaxin levels and PPGP during pregnancy were Relaxin Low back pain Pregnancy Systematic review Á Á Á included. Studies selection was conducted by two review- ers who screened firstly for titles, then for abstracts and finally for full articles. Risk of bias was assessed using the Introduction Newcastle–Ottawa scale and the quality of evidence by the guidelines proposed by the Cochrane back review group. Pregnancy-related pelvic girdle pain (PPGP) is a common Results 731 references were identified. Six articles met musculoskeletal disorder affecting approximately 20% of the inclusion criteria and were considered for this sys- all pregnant women [1]. Women who experience this dis- tematic review. The main reason for the studies exclusion order frequently present with reduced capacity for func- was PPGP related to gynaecological reasons. Five studies tional activities [2], and are three times more likely to have were case–control and one study was a prospective cohort. post-partum depressive symptoms [3]. Although the aeti- Four studies were ranked as high while two were ranked as ology of PPGP remains unknown, several studies suggest it low quality. Among the high quality studies, three found no is linked to increased pelvic mobility leading to pelvic joint association between PPGP and relaxin levels. instability and pain [4–6]. Validated biomechanical models of the pelvis support the concept of the sacroiliac joint (SIJ) being stabilized by active and passive structures surrounding the pelvis [7, 8]. D. Aldabe (&) M. Dawn Bussey School of PhysicalÁ Education, University of Otago, For instance, it has been shown that pelvic ligaments, such 56 Union Street, Dunedin 9016, New Zealand as the long dorsal, the iliolumbar and the sacrotuberous e-mail: [email protected] play key roles in pelvic stabilization such as, preventing excessive nutation and contranutation [9, 10]. Additionally, D. C. Ribeiro S. Milosavljevic Centre for PhysiotherapyÁ Research, School of Physiotherapy, active structures such as gluteus maximus, erector spinae, University of Otago, 325 Great King Street, Dunedin 9016, the biceps femoris and the thoracolumbar fascia attach to New Zealand these ligaments and to the sacroiliac joint (SIJ) and contribute to stabilization [10–12]. The sacrospinous and sacrotuber- D. C. Ribeiro Otago Polytechnic, Otago Institute of Sport and Adventure, ous ligaments also improve pelvic stability by providing 41 Harbour Terrace, Private Bag, Dunedin 1910, New Zealand proprioceptive information regarding pelvic position [13]. 123 Eur Spine J Consequently, some studies advocate the use of a pelvic belt 3. Study population: pregnant women in any stage of during pregnancy to structurally stabilise the pelvic girdle, pregnancy with no age limits. relative to the SIJ, as a useful intervention for reducing No language restriction was imposed. PPGP symptoms [14, 15]. However, the effectiveness of such intervention is still in debate [16]. Exclusion criteria were Relaxation of the pelvic ligaments is a physical change 1. Randomised and literature review studies, as well as, required during pregnancy and delivery. Such change thesis and dissertations; begins at the tenth to twelfth week of pregnancy [17] and is 2. Studies unrelated to PPGP or where PPGP has not considered to be a consequence of hormonal changes that been defined as a musculoskeletal disorder. occur about the same time [18]. Relaxin, a peptide hor- mone of the insulin-like growth factor family, has been associated with collagen remodelling in mammalians, Information sources including guinea pig, mouse, and human [19–21]. Secreted by the corpus luteum and placenta from early pregnancy, The electronic search was carried out using the following this hormone level increases to a considerable level during databases: Medline (1966 to July 2011), Amed (1985 to the first trimester, remaining steady at this level until late July 2011), EMBASE (1988 to July 2011), Proquest (July pregnancy and then becoming serologically undetectable in 2011), Web of Science (July 2011) and Scopus (July 2011). the first few days post-partum [22]. It is believed that relaxin increases pelvic laxity, and predisposes separation Search of the pubic symphysis, by altering the structure of colla- gen [23]. However, experimental studies have not shown a A literature search was carried out to identify all available direct relationship between high levels of relaxin and published articles on the relation and/or association increased pelvic mobility or peripheral joint mobility in between PPGP and relaxin levels. The identification of pregnant women [5, 24]. terms used in the search and the search strategy were Debate exists within the literature regarding the poten- developed in consultation with a health sciences librarian at tial role of the hormone relaxin in the manifestation of the University of Otago. The search terms were based on PPGP. While some studies argue relaxin loosens the pelvic keywords from previous publications as well as database- ligaments and increases instability [17, 23, 25, 26] others specific search terms [subject terms, subject headings (SH) do not accept that such relationship has been proven [1, and MeSh]. A string search was created adding ‘OR’ and 27]. These conflicting arguments have created a need for a ‘AND’ to combine the keywords and the subjects areas. systematic review to determine the level of evidence for The keywords used related to relaxin and PPGP were pregnant women with higher levels of relaxin being more ‘relaxin’ or ‘hormone’ or ‘reproductive hormone’ and likely to develop PPGP. To our knowledge, no previous ‘pelvic girdle pain’ or ‘low back pain’ or ‘pelvic pain’ or systematic review has addressed this question. ‘peripartum pelvic pain’ or ‘posterior pelvic pain’ or ‘pelvic insufficiency’. Additionally, one author (DA) scanned the reference lists of retrieved articles. Methodology Study selection The review was conducted following the guidelines described by the PRISMA Statement [28]. For more details All studies identified through the electronic search were Ò regarding to the methods of this systematic review, a stored in Endnote software (v.14 Thomson Reuters). protocol developed prior to the research was constructed Duplicate results were identified and removed by the and is available from the corresponding author upon principal investigator (DA). During screening by DA and request. DCR all titles were identified through electronic search as well as additional records identified through other sources. At the second stage of selection of studies, summary and Eligibility criteria full-text articles were screened, by the same two assessors (DA and DCR), against the predetermined inclusion and Inclusion criteria were exclusion criteria. Titles, abstracts and manuscript were not 1. Observational studies such as cohort, cross-sectional blinded for journal titles, authors and institutions, since and case–control; blinding has previously been shown not to affect the 2. Studies focusing on the causal relationship between study selection and data extraction [29]. If multiple PPGP and relaxin levels during pregnancy; reporting from the same study was found, only one study 123 Eur Spine J was included with all others referenced. Disagreement studies that quantified relaxin levels using enzyme-linked between the reviewers during the screening process was immunosorbent assay (ELISA) and presented its coeffi- determined by consensus. If consensus could not be reached cients of variation and serum samples were blindly ana- a third reviewer (MB) provided the majority opinion. lysed. Studies measuring relaxin concentrations using ELISA, without the above information described, or por- Data collection process cine radioimmunoassay were not awarded any point. This quality assessment restriction was due to the high vari- Data extraction from selected studies followed guidelines ability shown in studies using ELISA [39] and the con- proposed by the Cochrane Back Review Group [30]. This siderable differences observed between porcine and human was firstly performed by the principal investigator (DA) relaxin levels during pregnancy [40]. and subsequently confirmed by DCR. The following data Inter-rater reliability for assessment of risk of bias agree- were extracted: study design, year of the study, sample size ment between reviewers was measured by means of Kappa population, gestational