ObjectiveTo explore the relationship between prepregnancy obesity and the risk for cesarean delivery.MethodsThe population studied included 20,130 women with live births after 20 weeks gestation in central New York state between June 1, 1994, and May 31, 1995. Women who were obese before pregnancy were compare with nonobese women with regard to mode of delivery. Obesity was defined as body mass index (BMI) greater than 29. Separate analyses were conducted on the entire sample and on a subset of women with singleton pregnancies and no prior cesarean deliveries, as an estimate of the risk of primary cesarean delivery in obese women. Statistical analyses included χ2test, crude odds ratio (OR) with 95% confidence interval (CI), and adjusted OR with 95% CI, using logistic regression to control for confounding variables.ResultsThe adjusted OR was 1.64 (95% CI 1.46, 1.83) for obese women with singleton pregnancies and no prior cesarean deliveries to undergo cesarean delivery. The adjusted OR was 1.66 (95% CI 1.51, 1.82) for obese women in the entire sample to undergo cesarean delivery. In addition, increasing BMI was associated with increased risk for cesarean delivery.conclusionCompared with nonobese women, women who are obese before pregnancy are at increased risk for cesarean delivery. Preconceptional counseling regarding dietary and life-style nmodifications may alter this pattern.