Mode of delivery and offspring adiposity in late adolescence: The modifying role of maternal pre-pregnancy body size.

To study the association between mode of delivery and offspring BMI in late adolescence in a large cohort that predated the obesity epidemic, and assess the role of maternal pre-pregnancy BMI (ppBMI) in this association.We conducted a historical prospective study in the setting of the Jerusalem Perinatal Study (JPS), a population-based cohort that includes all 17,003 births to residents of West Jerusalem, between 1974 and 1976. Offspring's BMI at age 17 was obtained upon army recruitment and was available for 11,001 of cohort participants. The associations were examined using logistic regressions, adjusting for socio-demographic characteristics and for proxies for indication for C-Section birth. Analyses were then stratified by quartiles of ppBMI.C-Section was associated with offspring overweight/obesity, with adjusted OR of 1.44 (95%CI:1.14-1.82). Significant interaction of ppBMI with mode of delivery was observed, such that the associations of C-Section with overweight/obesity were limited to the upper quartile of ppBMI (adjusted OR = 1.70, 95%CI:1.18-2.43). Restricting the analyses to singleton first births and excluding pregnancies complicated with toxemia and gestational diabetes yielded similar findings.C-Section was positively associated with being overweight/obese at age 17. Importantly, ppBMI modified this association, with a significant association between C-Section and overweight/obesity evident only among offspring born to mothers in the highest ppBMI quartile. In light of the growing rates of obesity in women of reproductive age, these results should be considered in patient-doctor shared decisions related to selection of mode of delivery, in the absence of a clear medical indication.