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

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.