Impact of a Policy to Deliver at 39 Weeks for the Indication of Class III Obesity.

The aim of this study was to evaluate the effect of a policy to deliver at 39 weeks for class III obesity.This was a retrospective cohort study of women with class III obesity delivering at ≥ 37 weeks before (May 2012 to April 2014) and after the policy (September 2014 to August 2016). The primary outcome was the cesarean rate. Secondary outcomes included maternal morbidities and a neonatal morbidity composite. Modified Poisson regression was used to adjust for demographic differences between groups.The study included a total of 1,210 patients, 580 before the policy and 630 after the policy. Before and after the policy, cesarean rates were similar (41.6% vs. 47.1%; risk ratio [RR]: 1.13 [95% CI: 1.00-1.29]; adjusted RR [aRR]: 1.03 [95% CI: 0.92-1.14]). In adjusted comparisons of women undergoing labor induction, parous women had lower cesarean rates (aRR: 0.62; 95% CI: 0.41-0.94) but nulliparous women had higher cesarean rates (aRR: 1.32; 95% CI: 1.04-1.68) after the policy (P for interaction = 0.01). Rates of chorioamnionitis, endometritis, and cesarean wound infection were not different between groups. Composite neonatal morbidity was not different between pre- and postpolicy groups.A policy of delivery at 39 weeks for class III obesity did not affect overall cesarean rate or rates of maternal or neonatal morbidity. Further investigation should evaluate subsets of women who may have a higher cesarean rate with this policy.