Nonmedically indicated induction in morbidly obese women is not associated with an increased risk of cesarean delivery

Abstract

Background: The prevalence of morbid obesity (body mass index ≥40 kg/m²) in women aged 20-39 years was 7.5% in 2009 through 2010. Morbid obesity is associated with an increased risk of stillbirth compared with normal body mass index, especially >39 weeks' gestation. The data regarding increased risk of cesarean delivery associated with nonmedically indicated induction of labor compared to expectant management in morbidly obese women are limited.

Objective: We sought to compare the cesarean delivery rate of nonmedically indicated induction of labor with expectant management in morbidly obese women without other comorbidity.

Study design: This was a retrospective cohort study from the Consortium on Safe Labor of morbidly obese women with singleton, cephalic gestations without previous cesarean, chronic hypertension, or gestational or pregestational diabetes between 37 0/7 and 41 6/7 weeks' gestation. We examined maternal outcomes including cesarean delivery, operative delivery, third- or fourth-degree laceration, postpartum hemorrhage, and composite maternal outcome (any of: transfusion, intensive care unit admission, venous thromboembolism). We also examined neonatal outcomes including shoulder dystocia, macrosomia (>4000 g), neonatal intensive care unit admission, and composite neonatal outcome (5-min Apgar score <5, stillbirth, neonatal death, or asphyxia or hypoxic-ischemic encephalopathy). Adjusted odds ratios with 95% confidence intervals were calculated, controlling for maternal characteristics, hospital type, and simplified Bishop score. Analyses were conducted at early and full term (37 0/7 to 38 6/7 and 39 0/7 to 40 6/7 weeks' gestation, respectively). Women who delivered between 41 0/7 and 41 6/7 weeks' gestation were included as expectant management group.

Results: Of 1894 nulliparous and 2455 multiparous morbidly obese women, 429 (22.7%) and 791 (32.2%) had nonmedically indicated induction, respectively. In nulliparas, nonmedically indicated induction was not associated with increased risks of cesarean delivery and was associated with decreased risks of macrosomia (2.2% vs 11.0%; adjusted odds ratio, 0.24; 95% confidence interval, 0.05-0.70) at early term and decreased neonatal intensive care unit admission (5.1% vs 8.9%; adjusted odds ratio, 0.59; 95% confidence interval, 0.33-0.98) at full term compared with expectant management. In multiparas, nonmedically indicated induction compared with expectant management was associated with a decreased risk of macrosomia at early term (4.2% vs 14.3%; adjusted odds ratio, 0.30; 95% confidence interval, 0.13-0.60), cesarean delivery at full term (5.4% vs 7.9%; adjusted odds ratio, 0.64; 95% confidence interval, 0.41-0.98), and composite neonatal outcome (0% vs 0.6%; adjusted odds ratio, 0.10; 95% confidence interval, <.01-0.89) at full term.

Conclusion: In morbidly obese women without other comorbidity, nonmedically indicated induction was not associated with an increased risk of cesarean delivery.

Keywords: Foley balloon catheter; body mass index; composite neonatal morbidity; dinoprostone; expectant management; macrosomia; misoprostol; morbid obesity; neonatal intensive care unit admission; nonmedically indicated induction of labor; spontaneous labor; stillbirth.