841 Outcomes among women undergoing elective induction of labor compared to expectant management by maternal BMI

Abstract

To assess whether obstetric outcomes among women undergoing elective induction of labor vary based on maternal body mass index. We conducted a retrospective cohort study of singleton, non-anomalous, term deliveries in California between 2007-2011 to assess maternal and neonatal outcomes among nulliparous women undergoing elective induction of labor at 39 weeks compared with expectant management and further stratified by maternal pre-pregnancy body mass index (BMI). We defined elective induction of labor as induction of labor without medical indication and women with planned cesarean sections were excluded. Chi-squared and multivariable logistic regression analyses, controlling for maternal race/ethnicity, age, parity, education, and insurance status, were employed for statistical comparisons. In the cohort of 572,113 women, 6% were electively induced and 94% were expectantly managed. While rates of cesarean section are associated with increasing BMI, we found that women in the elective induction group were less likely to have a cesarean section than women who are expectantly managed across all BMI categories (aOR<1) (Table 1). Women with BMI 35-39.9 and BMI ≥40 had the lowest aOR for cesarean section (0.79 and 0.71, respectively). Rates of operative vaginal deliveries were higher in the elective induction group compared to expectant management across all BMI categories (aOR>1). Rates of shoulder dystocia were highest in women with BMI ≥40 (aOR 2.06, 95% CI 1.18-3.58). Rates of NICU admission and respiratory distress syndrome were lower in the elective induction group compared to expectant management, with no significant trends when stratified by BMI. In women undergoing elective induction of labor compared to expectant management, some obstetric outcomes vary when stratified by maternal pre-pregnancy BMI. As maternal BMI increases, managing with elective induction of labor is associated with lower adjusted odds ratio for cesarean section.