ARTICLE Colic Empirical Evidence of the Absence of an Association With Source of Early

Tammy J. Clifford, PhD; M. Karen Campbell, PhD; Kathy N. Speechley, PhD; Fabian Gorodzinsky, MD, FRCPC

Background: The etiology of infant colic remains un- Results: Of 856 , 733 (86%) completed the first known, despite an abundance of research on the topic. questionnaire and 617 (72%) completed the second ques- tionnaire. Overall, the prevalence of colic at 6 weeks was Objective: To determine whether has a 24%. No association was seen between the source of in- protective effect in colic’s development. fant nutrition and colic’s development. In multivariate analyses, higher levels of maternal trait anxiety (AOR, Design: A prospective cohort study of 856 - 1.22; 95% confidence interval [CI], 0.96-1.54), mater- infant dyads. Eligible participants included English- nal alcohol consumption at 6 weeks (AOR, 1.57; 95% CI, speaking adult residents of a region in Ontario, who gave 1.03-2.40), and shift work during pregnancy (AOR, 1.27; birth, at term, to a live singleton whose was 95% CI, 0.73-2.21) were associated with an increased like- appropriate for . Self-administered ques- lihood of colic, after controlling for feeding method, ma- tionnaires, mailed to mothers at 1 and 6 weeks post par- ternal age, and parity. In these same analyses, being mar- tum, requested information on several infant and mater- ried or having a common-law partner (AOR, 0.30; 95% nal factors, including source of infant nutrition (exclusively CI, 0.10-0.87) and being employed full-time during preg- breastfed, complementary fed, and exclusively formula fed). nancy (AOR, 0.60; 95% CI, 0.32-1.14) were associated Cases of colic were identified by applying modified Wes- with a reduced likelihood of colic. sel criteria to data recorded in the Barr Baby Day Diary or by interpreting responses to the Ames Cry Score. Conclusions: Breastfeeding did not have a protective effect on the development of colic. Although colic was Main Outcome Measures: Prevalence of colic among statistically associated with several variables, including breastfed, formula-fed, and complementary-fed ; preexisting maternal anxiety, much of colic’s etiology re- and adjusted odds ratios (AORs) reflecting the preva- mains unexplained. lence of colic among formula- and complementary-fed infants relative to those who were breastfed. Arch Pediatr Adolesc Med. 2002;156:1123-1128

NFANT COLIC remains enigmatic, most research efforts have relied on modi- despite its long history and its fied Wessel criteria.9 Estimates of colic’s relatively frequent occurrence. prevalence range from 5% to 40%, depend- While apparently innocuous, an ing on the definition and methods used.10 infant’s colic can prompt lasting Psychological,3,9,11 gastrointestinal,12-16 From the Departments of 1-6 17,18 Epidemiology and Biostatistics Iparental distress. The potential sever- andhormonal explanationsforcolic’sde- (Drs Clifford, Campbell, and ity of an episode of colic is highlighted by velopment have been suggested, but meth- Speechley), Paediatrics the fact that, for certain individuals, the odological shortcomings have restricted the (Drs Campbell, Speechley, and stress of caring for an inconsolable infant confidence that can be placed in the findings Gorodzinsky), and Obstetrics may trigger physical , such as that ofmanyworks.Thesemethodologicalissues & Gynecology (Dr Campbell), seen in .7,8 include inconsistent definitions for colic, the The University of Western Colic is characterized by excessive and failure to control for covariates, and poten- Ontario; Child Health Research inconsolable crying, hypertonicity, and tially biased assessments of exposure and/ Institute and Lawson Health wakefulness that cluster in the evening. Its oroutcomevariablesbecauseofnonprospec- Research Institute (Drs Campbell, Speechley, and onset usually occurs between the second and tive study designs. Consequently, there is Gorodzinsky), London; and sixth weeks of life, and its disappearance, contradictory evidence regarding colic’s eti- Children’s Hospital of Eastern around 3 months, is typically sudden and ology. This uncertainty, along with colic’s Ontario Research Institute, unexplained. Consensus has not been frequent occurrence, colic’s potential im- Ottawa (Dr Clifford). reached regarding a definition for colic, but pact on the family, and the absence of an

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1123

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 effective cure,19 underlines the importance of continued postpartum population. Each item has 4 possible response cat- research. egories that are scored from 0 to 3; thus, the total score can Although previous studies have considered dietary range from 0 to 30. The Edinburgh Postnatal Depression Scale causes of colic, methodological issues, including those pre- has optimal sensitivity and specificity when compared with viously outlined, have limited the comparability of stud- diagnoses of depression made through psychiatric inter- views.23,25 ies and, therefore, precluded definitive conclusions regard- Because adequate social support can attenuate the effects ing colic’s etiology. Our study was based on the hypothesis of stressful events, a shortened version of the Support Behav- that the prevalence of colic among breastfed infants would iors Inventory24 was incorporated into the first questionnaire. be lower than among those who were formula fed. The ra- A total score is calculated by summing the items on which an tionale for this hypothesis was derived from the nutri- affirmative response was indicated; thus, this construct is mea- tional and immunological superiority of breast milk, rela- sured on a continuous scale, with scores ranging from 0 to 11. tive to formula, and knowledge that the act of breastfeeding At 6 weeks post partum, mothers were asked to complete provides a unique opportunity for mother-child interac- 2 instruments that detailed their infant’s current cry/fuss be- 26 27 tion. By addressing some of the methodological issues noted haviors: the Barr Baby Day Diary and the Ames Cry Score. in earlier works, we believed that this study’s methodologi- The psychometric properties of the Barr Baby Day Diary are well documented.26 It consists of a series of time rulers that are shaded cal rigor would provide a degree of confidence in its find- by during the course of a day, for 7 consecutive days. ings that has not been previously conveyed. Four horizontal rulers represent each day; each ruler reflects 6 hours, with the smallest division on each ruler being 5 min- METHODS utes. Within each ruler, parents were asked to shade the ap- propriate time frame according to which behavior their infant Approval for this study was received from The University of was displaying at that time. Parents were provided with a key Western Ontario’s Review Board for Health Sciences Research that described the manner in which they were to shade the time Involving Human Subjects. An a priori sample-size calcula- ruler according to 6 mutually exclusive infant behaviors: sleep- tion indicated that 660 participants would need to be enrolled ing, awake and feeding, awake and content, awake and fuss- to detect a 10% difference in the proportion of colic among ing, awake and crying, and awake and sucking. Cases of colic breastfed and formula-fed infants, at a power of 80% and an ␣ were then identified as those infants whose cry/fuss behav- error of 5%.20 This estimate was then inflated by 30% to allow iors, as recorded in the diary, fulfilled modified Wessel crite- for nonparticipation and missing values, resulting in a final ria.9 For this study, a colicky infant was defined as one who sample size of 856. was “otherwise healthy and well fed, but who had paroxysms Data were collected from a cohort of 856 mother-infant of irritability, fussing, or crying lasting for 3 or more hours in dyads; the mothers were delivered of an infant in either of the any 1 day and occurring on 3 or more days in any 1 week.” 2 London hospitals providing obstetrical services. London, lo- Because we anticipated that some mothers would find the cated in southwestern Ontario, has a population of 330000 and demands of diary keeping to be onerous, particularly in low approximately 4600 births annually. Both hospitals are affili- socioeconomic status subgroups,26 mothers were also asked to ated with The University of Western Ontario and provide a full complete a short questionnaire-based instrument, the Ames Cry range of obstetrical services that are available 24 hours a day. Score.27 The Ames Cry Score is composed of 3 questions, each Eligible participants included English-speaking adult resi- with 4 response categories that are scored from 0 to 3. It asks dents of the region who gave birth, at term, to a live singleton about the frequency and average and maximum duration of an whose birth weight was appropriate for gestational age.21 Moth- infant’s cries during the past week. Overall scores, calculated ers were approached in person, before their discharge from the by summing the scores of individual items, range from 0 to 9, hospital. Those who wanted to participate provided written con- with a score of 3 or greater indicating colic. sent and an address to which surveys could be mailed. Reminder postcards were sent to all participants, and fol- Self-administered questionnaires, mailed to mothers at 1 low-up mailings were used if necessary.28 The postcards re- and 6 weeks post partum, solicited information on maternal quested that mothers simply return the questionnaire and the health behaviors, demographic variables, biological factors, and Ames Cry Score if they had been unable to complete the diary. the current source of infant nutrition (exclusively breastfed, Data were analyzed by the Statistical Product and Service complementary fed, and exclusively formula fed). Infants were Solutions 9.0 for Windows statistical program (SPSS Inc, Chi- considered exclusively breastfed if their only milk source was cago, Ill). The overall prevalence of colic at 6 weeks of age was breast milk (including expressed milk). Infants who received calculated; similar calculations provided the prevalence of colic any quantity of nonhuman milk along with breast milk were among exclusively breastfed, exclusively formula-fed, and categorized as complementary fed. Standardized instruments complementary-fed infants. For all analyses, the exposure vari- that assessed maternal anxiety,22 postnatal depression,23 and so- able was the source of infant nutrition at 1 week post partum, cial support24 were incorporated into the first questionnaire be- while the outcome, colic, was defined at 6 weeks post partum. cause these constructs have been suspected of playing a role This approach addressed one of the shortcomings of earlier in colic’s development and/or in mothers’ decisions to breast- works because it permitted an examination of the potential tem- feed. These instruments are described further. poral relationship between the source of infant nutrition and The State-Trait Anxiety Inventory22 is composed of 2 self- colic’s development. All variables were categorical, with the ex- report scales that measure 2 distinct anxiety concepts: state anxi- ceptions of labor and social support, maternal anxiety, and post- ety and trait anxiety. The Trait scale asks participants how they natal depression, which were measured on continuous scales. generally feel and is indicative of anxiety proneness. The State The 2-sample t test, the Mantel-Haenszel ␹2 test, and the scale asks participants how they currently feel and sensitively Fisher exact test were used, where appropriate, to analyze group indicates participants’ levels of transitory anxiety. Possible scores differences. The multivariate analysis was based on binomial range from 20 to 80 on each scale. The psychometric proper- logistic regression, using a backward stepwise procedure. For ties of the State-Trait Anxiety Inventory are well established.22 the regression analysis, trait and state anxiety scores were trans- The Edinburgh Postnatal Depression Scale23 is a 10-item formed from continuous to scaled variables. Each unit incre- self-report scale that was developed specifically for use in the ment on the scale represented a change of 10 points on the origi-

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1124

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 Mothers Who Were Table 1. Characteristics of the Sample Eligible and * Approached (N = 1019) Those Who Participants Dropped Out Characteristic (n = 733) (n = 123) P Value Consented Refused (n = 856 [84%]) (n = 163 [16%]) Marital status Single 53 (65) 28 (35) Ͻ.001 Partner† 680 (88) 95 (12) Completed Q1 Dropped Out at ≈1 wk (n = 123 [14%]) Mode of delivery (n = 733 [86%]) Vaginal 611 (85) 108 (15) .22 Cesarean section 118 (89) 14 (11) Maternal age, y Completed Q2 Dropped Out Ͻ20 14 (54) 12 (46) at ≈6 wk (n = 116 [16%]) (n = 617 [84%]) 20-34 611 (86) 100 (14) .001 Ն35 108 (92) 9 (8) Parity Completed the Barr Completed the Ames Primiparous 403 (86) 66 (14) .92 Baby Day Diary and the Cry Score Only Multiparous 330 (85) 56 (15) Ames Cry Score (n = 186 [30%]) (n = 431 [70%]) *Data are given as number (percentage) of mothers. Percentage are based on row totals. Figure 1. Study design. Q1 indicates questionnaire 1; Q2, questionnaire 2. †Being married or having a common-law partner.

nal 60-point continuous scale. The variable selection criterion 50 was set at PϽ.10, but statistical significance was assessed at PϽ.05. Regression results are expressed as adjusted odds ra- tios and 95% confidence intervals. 40

RESULTS 30 Eligible mothers were approached between January 15 and

September 16, 1999. Consent was received from 84% (856/ No. of Infants 20 1019) of eligible mothers who were approached. Re- sponse rates were above 80% at each stage of data collec- tion (Figure 1), with 72% of those who consented to 10 participate returning a completed study package at 6 weeks

post partum. Of those who participated at 6 weeks post par- 0 tum, 70% completed the Barr Baby Day Diary (Figure 1). 0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 Of the 733 participants who completed the first ques- Total Duration of Crying and Fussing During the Sixth Week of Life, min/wk tionnaire, 680 (93%) were married or had a common- Figure 2. Cry/fuss distribution at 6 weeks of age based on 431 completed law partner, 611 (83%) were delivered of an infant vagi- diaries (mean, 781.10 min/wk; SD, 461.10 min/wk). nally, and 611 (83%) were aged 20 to 34 years. Participants tended to be older (mean age, 29.4 years; SD, 4.9 years) 2 hours per day, the cry/fuss behavior of some infants and were more likely to be married than those who gave was truly excessive, with one mother recording that her consent but did not complete questionnaires (ie, drop- infant cried/fussed for 45 hours during that week. outs) (Table 1). Multiparous mothers were underrep- The prevalence of colic among exclusively breast- resented in the study sample, relative to the general popu- fed, exclusively formula-fed, and complementary-fed in- lation (45% vs 58.7%) (Ontario Livebirth Database, 1997). fants was 23%, 21%, and 29%, respectively (Table 2). In addition, this sample was well educated, with 75% of In univariate analyses (Table 2), there was no statisti- mothers indicating that they had completed at least some cally significant relationship between the source of early postsecondary education. Almost 70% of the partici- infant nutrition, measured at 1 week post partum, and pants were breastfeeding their infant at 1 week post par- the development of colic at 6 weeks post partum (P=.50). tum, and a similar proportion of our study sample re- Only those additional variables with PϽ.10 are listed in sponded that their annual household income was in excess Table 2. For the multivariate analysis (Table 3), we con- of Can $40000. trolled for several variables: source of early infant nutri- Overall, the prevalence of colic was 24%. When ex- tion as the risk factor of interest; maternal age and par- amined separately, the prevalence of colic based on in- ity, because the experiences of these populations were terpretation of the Barr Baby Day Diary was 23%, while expected to differ qualitatively; and maternal trait anxi- that derived from the Ames Cry Score was 29%. The dis- ety and shift work, because these variables had been iden- tribution of cry/fuss behaviors (Figure 2) was derived tified as classic confounders20 (ie, statistically signifi- from detailed examination of the 431 diaries that were cantly associated with the risk factor and the outcome). returned. The mean amount of crying/fussing recorded Maternal state anxiety was also identified as a classic con- during an infant’s sixth week of life was more than 13 founder, but, owing to its high correlation with trait anxi- hours (SD, 7.7 hours). While this is, on average, less than ety (r=0.80), it was permitted to enter the multivariate

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1125

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 Table 2. Factors Associated With the Development of Colic Table 3. Factors Associated With the Development of Colic at 6 Weeks of Age: Univariate Analysis* at 6 Weeks of Age: Multivariate Analysis

Colic Factor AOR (95% CI)*

Factor Yes No P Value Source of infant nutrition (at 1 wk) Breast milk only† 1.00 Source of infant nutrition (at 1 wk) Formula only 0.94 (0.54-1.64) Breast milk only 101 (23) 330 (77) Breast milk and formula 1.43 (0.74-2.76) Formula only 25 (21) 93 (79) .50 Marital status Breast milk and formula 19 (29) 47 (71) Single† 1.00 Marital status Partner‡ 0.30 (0.10-0.87) Single 11 (38) 18 (62) .07 Maternal alcohol consumption Partner† 134 (23) 452 (77) at 6 wk post partum Employment status (2 mo before None† 1.00 being delivered of an infant) Some 1.57 (1.03-2.40) Homemaker 22 (22) 77 (78) Employment status (2 mo before being delivered Student 2 (12) 14 (88) of an infant) Unemployed 7 (41) 10 (59) .01 Homemaker† 1.00 Full-time 74 (20) 289 (80) Student 0.18 (0.02-1.76) Part-time 40 (33) 80 (67) Unemployed 1.14 (0.31-4.20) Shift work (before being delivered Full-time 0.60 (0.32-1.14) of an infant) Part-time 1.39 (0.70-2.78) No 112 (22) 400 (78) .03 Yes 33 (32) 70 (68) *Values adjusted for maternal age, parity, shift work, trait anxiety, and all State anxiety, mean (SD) 35.97 (9.7) 33.04 (10.0) .003 factors listed in the table. AOR indicates adjusted odds ratio; CI, confidence Trait anxiety, mean (SD) 37.63 (8.5) 35.30 (8.6) .004 interval. †Reference. *Data are given as number (percentage) unless otherwise indicated. Values ‡Being married or having a common-law partner. may not total 617 because of missing data. Percentages are based on row totals. The factors not significantly related to colic at 6 weeks of age are as follows: hospital of delivery, infant sex, mode of delivery, obstetrical anesthesia or analgesia, attendance at prenatal classes, rooming-in, family history of atopy, our decision to present only those findings derived from maternal smoking during pregnancy, residing with a smoker, maternal alcohol the multivariate model that did not include pacifier use. use during pregnancy, maternal caffeine consumption during pregnancy, anticipated return to work, maternal educational level, annual household income, pacifier use, social support, labor support, and postnatal depression. COMMENT †Being married or having a common-law partner. Despite using prospective methods, an objective case defi- nition, a population-based sample, and multivariate tech- model only if it satisfied the variable selection criteria. niques, our results failed to document any relationship With the exception of maternal trait anxiety (P=.007), between the source of early infant nutrition and colic’s none of these factors significantly predicted colic’s de- development. The absence of a protective effect of breast- velopment. feeding on colic’s development is robust across time, ge- On the other hand, several other variables did ography, and study design.1,7,11,27,30-35 These observa- prove predictive (Table 3). If a mother was employed or tions lend support to the belief that organic causes (eg, attended school full-time before being delivered of an protein intolerance) are responsible for only a small sub- infant, her infant was significantly less likely to exhibit group of cases of colic.36 This, along with the absence of colic. Infants born to mothers who were married or had a marked effect of the practice of on-demand nursing on a common-law partner were 70% less likely to exhibit the cry/fuss behaviors of colicky infants,37,38 implies that colic, relative to infants born to single mothers. El- infants with colic are intrinsically different from infants evated levels of postnatal depression also seemed pro- without colic. Thus, recommendations for the early wean- tective against colic’s development, but this association ing of colicky infants39 are unfounded. failed to reach statistical significance (P=.08). Abstain- Our results suggest that almost 1 in 4 infants expe- ing from alcohol was also statistically associated with a rienced colic at 6 weeks of age. Collection of cry/fuss data reduced likelihood of colic; however, because these 2 at this time point was expected to capture most cases of variables were measured at the same time point (ie, at 6 colic because the sixth week of life represents the peak weeks), we cannot infer whether mothers did not begin of infant crying.40-42 The noted discrepancy in the preva- drinking if their infants were not colicky or whether the lence of colic assessed prospectively (by the Barr Baby reverse is true. Day Diary), compared with an instrument that relied on Finally, because pacifier use was expected to affect 1-week recall (the Ames Cry Score), supports the no- breastfeeding and infant cry/fuss behavior, we consid- tion that retrospective estimates exceed those derived pro- ered it as a potential confounder. In the end, our results spectively.9,11,30-32,43-49 Nevertheless, the Ames Cry Score did not change, regardless of whether pacifier use was is reasonably valid for identifying cases of colic when di- included in the multivariate model. This observation, rectly compared with the Barr Baby Day Diary (T.J.C., taken along with recent evidence that pacifier use is not M.K.C., K.N.S., and F.G., unpublished data, 2000). causally related to early weaning and does not markedly Given the similarity in the crying patterns of in- affect the daily duration of cry/fuss behavior,29 prompted fants with and without colic,31 one limitation of this study

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1126

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 is its reliance on modified Wessel criteria. At its peak, What This Study Adds the median amount of crying is 2.75 h/d, but there exists substantial intraindividual and interindividual variability.38,40,41 The distribution of cry/fuss behaviors Colic is a relatively common condition of early infancy, derived from this cohort (Figure 2) confirms that characterized by excessive and inconsolable crying. Al- though some previous studies have suggested that, in most there is substantial variability in this behavior. Thus, it cases, food intolerance is to blame, methodological short- is still unknown whether the modified Wessel criteria comings of these works have limited the confidence with describe a clinically meaningful subgroup of crying which their findings could be interpreted. Because nu- infants.37,41 merous intervention strategies are based on dietary in- Elevated levels of maternal anxiety have received con- compatibility theories, there is a need to determine siderable attention as a contributing factor in colic’s de- whether this focus is justified. velopment.3,9,11,34,50 In our multivariate model, elevated By using prospective methods in a community levels of maternal trait anxiety, measured at 1 week post sample of infants, this study addressed many of the meth- partum, predicted colicky behavior at 6 weeks; how- odological issues of previous works. In doing so, the study ever, this finding failed to reach statistical significance. provided evidence that almost 1 in 4 infants exhibited colicky behavior at 6 weeks of age. Multivariate analy- In addition, the clinical importance of this association is ses suggested that breastfeeding was not protective in col- limited given that the multivariate model predicted only ic’s development, and, although colic was statistically as- 9% of cases of colic. Moreover, the levels of trait anxiety sociated with several factors, including preexisting reported in our sample (Table 2) were not remarkable maternal anxiety, the clinical importance of this find- and correspond well with levels seen in another sample51 ing is limited given that the final model explained less of mothers of healthy children. than 10% of the variance seen. So, while the origins of There has also been debate about the connection be- colic remain a mystery, its clinical salience cannot be tween maternal health behaviors and colic’s develop- questioned. ment. In contradiction to previous works,32,52-54 data col- lected in this study failed to implicate an infant’s exposure to tobacco smoke in the etiology of colic. In addition, no association was noted between an infant’s colic and the should provide comfort to parents: we provide further mother’s consumption of caffeinated beverages. On the evidence that parents are not responsible for their in- other hand, a statistically significant association was seen fants’ colic. Of course, much work remains to be done between maternal alcohol consumption (at 6 weeks post to improve our understanding of the underlying pro- partum) and an infant’s colicky behavior; however, be- cesses responsible for colic and to minimize their poten- cause these variables were measured concurrently, a tem- tial effects on families, particularly those who are al- poral relationship cannot be inferred. Nevertheless, this ready at elevated risk of distress from less-than-ideal may hint at the potential sequelae of an episode of colic, financial, social, and/or medical circumstances. If, as some by suggesting that an infant’s excessive crying may prompt suggest,55,56 the origins of colic can be found in dis- the mother to adopt unhealthy behaviors, such as drink- jointed rhythms, future research needs to determine an ing, as a means to cope. optimal manner for identifying infants who are at an el- In a novel finding, our study suggests that infants evated risk of state regulatory disorders and to deter- born to mothers who were married or had a common- mine methods for entraining their rhythms. Colic’s rela- law partner were 70% less likely to develop colic, rela- tively frequent occurrence and potential sequelae tive to infants born to single mothers. The persistence command our continued attention. of this variable in the multivariate model suggests that the positive influence of a supportive partner is indepen- Accepted for publication August 8, 2002. dent of other factors. Coping skills can be enhanced by This study was supported by a Department of Pediat- social support that is provided by a partner, family mem- rics’ Graduate Student Bursary from The University of bers, or friends.24 As such, one might speculate that pro- Western Ontario, London (Dr Clifford); an Ontario vision of additional support to single mothers during the Graduate Scholarship (Science & Technology) (Dr Clif- early postpartum period might have tangible benefits to ford); an Ontario Graduate Scholarship (Dr Clifford); the mother and child. Future research may want to exam- Middlesex-London Breastfeeding Committee, London (Dr ine this issue in detail. Clifford); an Internal Research Award from the London Admittedly, because the participants in our study Health Sciences Centre, London (Dr Speechley); and an were, on average, well educated and relatively affluent, Internal Research Award from the Child Health Research our findings may not generalize to populations that dif- Institute, Children’s Hospital of Western Ontario, London fer in their socioeconomic background and/or access to (Dr Campbell). health care. Nevertheless, the internal validity of our study We thank the mothers and infants who made this study is high because of the inclusive nature of the study popu- possible through their invaluable contributions and sup- lation and high response rates. This internal validity lends port; Ron Barr, MDCM, for sharing the Barr Baby Day Di- support to our conclusion that, in most cases, recom- ary; Ruth Elliott, RN, PhD, for making us aware of the Ames mendations to alter an infant’s diet in the hope of ame- Cry Score; Anne Pincombe, RN, and Sherry Foran, RN, for liorating his or her colic are unfounded. facilitating our access to the postpartum wards; and Romina Although continued uncertainty about colic’s eti- Reyes, MSc, Caroline Corrigan, BA, and Rachel Silver, MD, ology may be viewed in a negative light, our findings MSc, for their assistance during recruitment.

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1127

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021 Corresponding author and reprints: Tammy J. Clif- 27. Ames E, Bradley C. Infant and characteristics related to parents’ reports ford, PhD, Children’s Hospital of Eastern Ontario Re- of colic in one-month-old and three-month-old infants. Paper presented at: Ca- nadian Psychological Association Meeting; June 10, 1983; Winnipeg, Manitoba. search Institute, 401 Smyth Rd, Ottawa, Ontario, Canada 28. Dillman DA. Mail and Internet Surveys: The Tailored Design Method. New York, K1H 8L1 (e-mail: [email protected]). NY: John Wiley & Sons Inc; 2000. 29. Kramer MS, Barr RG, Dagenais S, et al. Pacifier use, early weaning and cry/fuss behavior: a randomized controlled trial. . 2001;286:322-326. REFERENCES 30. Hide DW, Guyer BM. Prevalence of infant colic. Arch Dis Child. 1982;7:559-560. 31. Thomas DW, McGillian K, Eisenberg LD, Lieberman HW, Rissman EM. Infantile 1. Forsyth BWC, Leventhal JM, McCarthy PL. Mothers’ perceptions of problems of colic and type of milk feeding. AJDC. 1987;141:451-453. feeding and crying behaviors. AJDC. 1985;139:269-272. 32. Canivet C, Hagander B, Jakobsson I, Lanke J. Infantile colic: less common than 2. Thompson PE, Harris CC, Bitowski BE. Effects of infant colic on the family: im- previously estimated? Acta Paediatr. 1996;85:454-458. plications for practice. Issues Compr Pediatr Nurs. 1986;9:273-285. 33. Barr RG, Kramer MS, Pless IB, Boisjoly C, Leduc D. Feeding and temperament as 3. Miller AR, Barr RG, Eaton WO. Crying and motor behavior of six-week-old in- determinants of early infant crying/fussing behavior. Pediatrics. 1989;84:514-521. fants and postpartum maternal mood. Pediatrics. 1993;92:551-558. 34. Rautava P, Helenius H, Lehtonen L. Psychosocial predisposing factors for in- 4. Rautava P, Lehtonen L, Helenius H, Sillanpaa M. Infantile colic: child and family fantile colic. BMJ. 1993;307:600-604. three years later. Pediatrics. 1995;96:43-47. 35. Lucas A, St James–Roberts I. Crying, fussing and colic behavior in breast- and 5. Raiha H, Lehtonen L, Korhonen T, Korvenranta H. Family life 1 year after infan- bottle-fed infants. Early Hum Dev. 1998;53:9-18. tile colic. Arch Pediatr Adolesc Med. 1996;150:1032-1036. 36. Gormally SM, Barr RG. Of clinical pies and clinical clues: proposal for a clinical 6. Canivet C, Jakobsson I, Hagander B. Infantile colic: follow-up at four years of approach to complaints of early crying and colic. Ambulatory Child Health. 1997; age: still more “emotional.” Acta Paediatr. 2000;89:13-17. 3:137-153. 7. Singer JL, Rosenberg NM. A fatal case of colic. Pediatr Emerg Care. 1992;8:171- 37. Barr RG, Elias MF. Nursing interval and maternal responsivity: effect on early 172. infant crying. Pediatrics. 1988;81:529-536. 8. Levitzky S, Cooper R. Infant colic syndrome: maternal fantasies of aggression 38. Hunziker UA, Barr RG. Increased carrying reduces infant crying: a randomized and infanticide. Clin Pediatr (Phila). 2000;39:395-400. controlled trial. Pediatrics. 1986;77:641-648. 9. Wessel MA, Cobb JC, Jackson EB, Harris GS, Detwiler AC. Paroxysmal fussing 39. Iacono G, Carroccio A, Montalto G, et al. Severe infantile colic and food intolerance: in infancy, sometimes called “colic.” Pediatrics. 1954;14:421-433. a long-term prospective study. J Pediatr Gastroenterol Nutr. 1991;12:332-335. 10. Lucassen PL, Assendelft WJ, van Eijk JT, Gubbels JW, Douwes AC, van Geldrop 40. Brazelton TB. Crying in infancy. Pediatrics. 1962;29:579-588. WJ. Systematic review of the occurrence of infantile colic in the community. Arch 41. Barr RG, Rotman A, Yaremko J, Leduc D, Francoeur TE. The crying of infants Dis Child. 2001;84:398-403. with colic: a controlled empirical description. Pediatrics. 1992;90:14-21. 11. Paradise JL. Maternal and other factors in the etiology of colic. JAMA. 1966; 42. St James–Roberts I, Halil T. Infant crying patterns in the first year: normal com- 197:123-131. munity and clinical findings. J Child Psychol Psychiatry. 1991;32:951-968. 12. Campbell JP. Dietary treatment of infant colic: a double-blind study. JRCollGen 43. Illingworth RS. Three months’ colic. Arch Dis Child. 1954;29:165-174. Pract. 1989;39:11-14. 44. Boulton TJ, Rowley MP. Nutritional studies during early childhood, III: inci- 13. Jakobsson I, Lindberg T. Cow’s milk proteins cause infantile colic in breast-fed dental observations of temperament, habits and experiences of ill-health. Aust infants: a double-blind crossover study. Pediatrics. 1983;71:268-271. Paediatr J. 1979;15:87-90. 14. Jakobsson I, Lindberg T, Benediktsson B, Hansson BG. Dietary bovine beta- 45. Rubin SP, Prendergast M. Infantile colic: incidence and treatment in a Norfolk lactoglobulin is transferred to human milk. Acta Paediatr Scand. 1985;74:342- community. Health Dev. 1984;10:219-226. 345. 46. Stahlberg M. Infantile colic: occurrence and risk factors. Eur J Pediatr. 1984; 15. Lothe L, Lindberg T. Cow’s milk whey protein elicits symptoms of infantile colic 143:101-111. in colicky formula-fed infants: a double-blind crossover study. Pediatrics. 1989; 47. 83:262-266. Hogdall CK, Vestermark B, Birch M, Plenov G, Toftager-Larsen K. The signifi- 16. Clyne PS, Kulczycki A. Human breast milk contains bovine IgG: relationship to cance of pregnancy, delivery and postpartum factors for the development of in- infant colic? Pediatrics. 1991;87:439-444. fantile colic. J Perinat Med. 1991;19:251-257. 17. Lothe L, Ivarsson SA, Ekman R, Lindberg T. Motilin and infantile colic: a pro- 48. Lehtonen L, Korvenranta H. Infantile colic: seasonal incidence and crying pro- spective study. Acta Paediatr Scand. 1990;79:410-416. files. Arch Pediatr Adolesc Med. 1995;149:533-536. 18. Weissbluth M, Weissbluth L. Colic, sleep inertia, melatonin and circannual rhythms. 49. Crowcroft NS, Strachan DP. The social origins of infantile colic: questionnaire Med Hypotheses. 1992;38:224-228. study covering 76,747 infants. BMJ. 1997;314:1325-1328. 19. Garrison MM, Christakis DA. A systematic review of treatments for infant colic. 50. Carey WB. Maternal anxiety and infantile colic: is there a relationship? Clin Pediatrics. 2000;106:184-190. Pediatr (Phila). 1968;7:590-595. 20. Kelsey JL, Whittemore AS, Evans AS, Thompson WD. Methods in Observational 51. Speechley KN, Noh S. Surviving childhood cancer, social support, and parents’ Epidemiology. New York, NY: Oxford University Press Inc; 1996. psychological adjustment. J Pediatr Psychol. 1992;17:15-31. 21. Arbuckle TE, Wilkins R, Sherman GJ. Birthweight percentiles by gestational age 52. Matheson I. The effect of smoking on lactation and infantile colic. JAMA. 1989; in Canada. Obstet Gynecol. 1993;81:39-48. 261:42-43. 22. Spielberger CD, Gorsuch RL, Luschene R. The State-Trait Anxiety Inventory. Palo 53. Sondergaard C, Henriksen TB, Obel C, Wisborg K. Smoking during pregnancy Alto, Calif: Consulting Psychologists Press; 1970. and infantile colic. Pediatrics. 2001;108:342-346. 23. Cox JL, Holden JM, Sagovsky R. Detection of postnatal depression: develop- 54. Reijneveld SA, Brugman E, Hirasing RA. Infantile colic: maternal smoking as po- ment of the 10-item Edinburgh Postnatal Depression Scale. Br J Psychiatry. 1987; tential risk factor. Arch Dis Child. 2000;83:302-303. 150:782-786. 55. White BP, Gunnar MR, Larson MC, Donzella B, Barr RG. Behavioral and physi- 24. Brown MA. Social support during pregnancy: a unidimensional or multidimen- ological responsivity, sleep and patterns of daily cortisol production in infants sional construct. Nurs Res. 1986;35:4-9. with and without colic. Child Dev. 2000;71:862-877. 25. Harris B, Huckle P, Thomas R, Jones S, Fung H. The use of rating scales to iden- 56. Larson MC, White BP, Cochran A, Donzella B, Gunnar MR. Dampening of the tify post-natal depression. Br J Psychiatry. 1989;154:813-817. cortisol response to handling at three months in human infants and its relation- 26. Barr RG, Kramer MS, Boisjoly C, McVey-White L, Pless IB. Parental diary of in- ship to sleep, circadian cortisol activity and behavioral distress. Dev Psycho- fant cry and fuss behavior. Arch Dis Child. 1988;63:380-387. biol. 1998;33:327-337.

(REPRINTED) ARCH PEDIATR ADOLESC MED/ VOL 156, NOV 2002 WWW.ARCHPEDIATRICS.COM 1128

©2002 American Medical Association. All rights reserved. Downloaded From: https://jamanetwork.com/ on 09/26/2021