Association of mode of delivery with offspring pubertal development in Project Viva: a prospective pre-birth cohort study in the USA.

study questionIs cesarean delivery associated with earlier offspring pubertal development? SUMMARY ANSWER: We identified that boys born by cesarean delivery developed puberty earlier, evidenced by an earlier age at peak height velocity and earlier attainment of puberty score > 1, than boys born by vaginal delivery. WHAT IS KNOWN ALREADY: Cesarean delivery is posited to have long-term effects on health outcomes. However, few studies have examined whether mode of delivery is related to pubertal development. STUDY DESIGN, SIZE, DURATION: Prospective pre-birth cohort study consisting of 1485 mother-child pairs enrolled during pregnancy from obstetric practices and followed up until early adolescence (median age 12.9 years). Participant inclusion required data on mode of delivery and at least one measure of pubertal development. PARTICIPANTS/MATERIALS, SETTING,

methodsParticipants are children from the Project Viva study. We abstracted information on delivery mode from electronic medical records from children followed since birth (1999-2002) and examined the following markers of pubertal development: age at peak height velocity (APHV); age at menarche (girls only); parent-reported pubertal development score; and child-reported pictograph Tanner pubic hair staging. We used multivariable regression models to examine associations of delivery mode with these four pubertal indices, adjusting for the following confounders: demographic and socioeconomic factors; maternal height, pre-pregnancy BMI, total gestational weight gain, pregnancy conditions, parity, and maternal age at menarche; paternal height and BMI; gestational age at delivery and birthweight-for-gestational-age z-score. MAIN RESULTS AND THE ROLE OF CHANCE: In this study, 23.2% of children were born by cesarean delivery. Girls had an earlier APHV, had a higher pubertal score throughout childhood and in early adolescence, and were more likely to attain puberty score >1 and Tanner pubic hair Stage >1 earlier compared to boys. Mean (SD) age at menarche in girls was 12.4 (1.0) years. Boys born by cesarean delivery had significantly earlier APHV (β -0.23 years; 95% CI -0.40, -0.05) and higher risk of earlier attainment of puberty score > 1 (hazard ratio 1.09; 95% CI 1.01, 1.19) than boys born by vaginal delivery, after adjusting for confounders. These associations were not mediated by pre-pubertal BMI and were similar for planned (no labor) and unplanned (labor) cesarean delivery. No associations were observed between delivery mode and time to attain Tanner pubic hair Stage > 1 in boys. In girls, mode of delivery was not associated with any of the measured pubertal development markers. LIMITATIONS, REASONS FOR CAUTION: This study used, as secondary outcomes, parent- and child-reported measures of pubertal development, which may be more prone to error and misclassification than information collected by trained observers or physicians during clinical examinations. The findings may also not be generalizable to populations from different settings, because all participants lived in one geographic area, were well educated, and had health care. WIDER IMPLICATIONS OF THE

findingsOur findings provide support for cesarean delivery as a potential indicator of identifying children who are likely to experience earlier pubertal development; however, more studies are needed to confirm or refute these observations. STUDY FUNDING/COMPETING INTEREST(S): The project was funded by grants from the National Institutes of Health. The authors have no financial relationships or competing interests to disclose. TRIAL REGISTRATION NUMBER: N/A.