881: Term elective induction of labor and risk of cesarean delivery in nulliparous obese women

Abstract

Current data are conflicting on whether elective induction of labor increases the rate of cesarean delivery (CD) in nulliparous obese women. The purpose of this study is to characterize the risk of cesarean delivery in obese nulliparas undergoing term elective induction of labor versus expectant management. This is a retrospective cohort study of singleton, vertex, nonanomalous deliveries among nulliparous obese women (BMI ≥30) in California in 2008 using linked hospital discharge and vital statistics data (N=25,964). Women with diabetes or other chronic disease complicating pregnancy were excluded from this analysis. We compared an elective induction of labor as defined by the Joint Commission at 38, 39, or 40 weeks’ gestation with expectant management, stratified by WHO obesity class. The outcome of interest was CD. We used bivariate (chi-square) statistics and developed multivariate logistic regression models controlling for maternal age, ethnicity, education level, initiation of prenatal care in the first trimester, and insurance status. The proportions of women undergoing CD were not significantly different between elective induction of labor and expectant management groups among women with a BMI between 30-35 or between 35-39 at any term gestational age. However, in morbidly obese women (BMI ≥40), elective induction of labor at 38 weeks was associated with lower odds of CD compared to expectant management (odds ratio [OR] 0.32, 95% confidence interval [CI] 0.14-0.75; 38 weeks OR 0.62, 95% CI 0.39-0.98). Among nulliparous obese women, elective induction of labor at term is not associated with higher odds of CD compared to expectant management. Furthermore, early term elective induction of labor is significantly associated with lower odds of CD in nulliparous women with a BMI of 40 or greater.