Maternal pre-pregnancy overweight and obesity and the risk of cesarean delivery in nulliparous women

PURPOSE: To examine the effect of maternal pre-pregnancy overweight and obesity on the risk of term cesarean delivery in nulliparous women. METHODS: The authors examined data from 641 nulliparous women with a term pregnancy that participated in the Pregnancy, Infection, and Nutrition Study from 1995 to 2002. Unadjusted and adjusted risk ratios and 95% confidence intervals (CI) were computed for normal weight (BMI 19.8-26.0 kg/m(2)), overweight (BMI 26.1-29.0 kg/m(2)), and obese (BMI > 29.0 kg/m(2)) women. Normal weight women served as the referent population. RESULTS: The unadjusted risk ratio for cesarean delivery for overweight women compared with normal weight women was 1.4 (95% Cl, 0.97, 2.1) and for obese women compared with normal weight women was 1.4 (95% Cl, 1.03, 2.0). After controlling for maternal height, education, weight gain during pregnancy, and labor induction, the adjusted risk ratio for cesarean delivery among overweight women was 1.2 (95% Cl, 0.8, 1.8). The adjusted risk ratio for obese women was 1.5 (95% Cl, 1.05, 2.0). CONCLUSION: Our analysis confirms that there is a moderate association between maternal pre-pregnancy obesity and an unplanned term cesarean delivery. However, the risk is not as large as previously reported.