The influence of obesity and diabetes on the risk of cesarean delivery

Objective To determine the influence of pregravid obesity and diabetes on cesarean delivery (CD) risk. Study design Women with singleton pregnancies of 23 weeks or more estimated gestational age who were undergoing a trial of labor January 1997 through June 2001 were categorized by pregravid body mass index (underweight [<19.8 kg/m2], normal [19.8-25 kg/m2], overweight [25.1-30 kg/m2], obese [>30 kg/m2]). Diabetes (DM) was divided into categories of gestational, treated with diet modification (A1GDM) or insulin (A2GDM), and pregestational (PDM). Prior CDs were excluded. CD rates for each group were compared in univariate analyses stratified by estimated gestational age (term, preterm, total). Other variables examined included DM, macrosomia (birth weight 4500 g or more), induction, and parity. Multiple regression included significant variables to predict the influence of diabetes and obesity on CD risk. Results Records for 12,303 deliveries were evaluated (obese: 2828 [22.9%]; overweight: 2605 [21.2%]; A1GDM: 270 [2.2%]; A2GDM: 93 [0.8%]; PDM: 126 [1%]). Obese and overweight subjects had a higher risk for CD, compared with normal subjects (13.8% and 10.4% versus 7.7%, P< .0001 for each). Other CD risk factors were macrosomia (25% versus 9.4%), nulliparity (16.5% versus 4.7%), induction (17.4% versus 8.3%), diabetes (A1GDM: 16.7% versus 9.4%; A2GDM: 24.7% versus 9.5%; PDM: 34.9% versus 9.3%) and black race (10.7% versus 8.8%) (P< .0001 for each). In mutiple regression models including term deliveries, obesity and PDM were independent CD risk factors ([adjusted OR overweight: 1.5, P< .0001; adjusted OR PDM: 2.9, P = .01]; [adjusted OR obese: 2.4, P< .0001, PDM: 2.9, P = .0002]). Conclusion Pregravid obesity and diabetes independently increase the risk for CD. Given the disparate prevalence of obesity and diabetes in the United States, body habitus has a significantly larger impact on CD risk.