Maternal pre-pregnancy overweight status and obesity as risk factors for cesarean delivery

Objective. To determine the extent to which, if at all, maternal pre-pregnancy adiposity and other anthropometric factors are related to risk of cesarean delivery. Methods. This hospital-based prospective cohort study included 738 nulliparous women who initiated prenatal care prior to 16 weeks gestation. Participants provided information about their pre-pregnancy weight and height and other sociodemographic and reproductive covariates. Labor and delivery characteristics were obtained from maternal and infant medical records. Risk ratios (RR) and 95% CI were estimated by fitting generalized linear models. Results. The proportion of cesarean deliveries in this population was 26%. Women who were overweight ( BMI 25.00 - 29.99 kg/m(2)) were twice as likely to deliver their infants by cesarean section as lean women ( BMI <20.00 kg/m(2)) (RR = 2.09; 95% CI 1.27 - 3.42). Obese women ( BMI >= 30.00 kg/m(2)) experienced a three-fold increase in risk of cesarean delivery when compared with this referent group (RR = 3.05; 95% CI 1.80 - 5.18). The joint association between maternal pre-pregnancy overweight status and short stature was additive. When compared with tall ( height >= 1.63 m), lean women, short (<1.63 m), overweight ( BMI >= 25.00 kg/m(2)) women were nearly three times as likely to have a cesarean delivery (RR = 2.79; 95% CI 1.72 - 4.52). Conclusion. Our findings suggest that nulliparous women who are overweight or obese prior to pregnancy, and particularly those who are also short, have an increased risk of delivering their infants by cesarean section.