Pregnancy Outcomes Among Obese Women and Their Offspring by Attempted Mode of Delivery.

Objective: To compare maternal and neonatal morbidities among obese women and their offspring by attempted delivery approach.

Methods: We performed a retrospective cohort study of 47,372 obese women at delivery (body mass index 30 or greater) eligible for vaginal delivery who were carrying singleton vertex fetuses at 37 weeks of gestation or greater. Prior cesarean delivery, congenital anomalies, and antepartum stillbirth were exclusion criteria. We analyzed outcomes by attempted delivery route and stratified by parity. The composite maternal outcome included intensive care admission, death, hemorrhage, transfusion, or thromboembolism. The neonatal composite included intensive care unit admission, death, seizure, ventilator use, birth injury, or asphyxia. Adjusted relative risks (RRs) and 95% confidence intervals (CIs) were calculated using Poisson regression.

Results: Among nulliparous women attempting vaginal delivery (n=15,268), the success rate was 72.6% and among parous women (n=23,426), it was 93.7%. The maternal composite outcome rate was not statistically higher among nulliparous women (7.7% compared with 4.2% [adjusted RR 1.58, 95% CI 0.96-2.59]) but it was among parous women (7.6% compared with 2.5% [adjusted RR 2.45, 95% CI 1.23-4.90]) attempting vaginal delivery related to hemorrhage, blood transfusion, or both. In contrast, the neonatal composite outcome rate was lower in parous women (6.0% compared with 11.6% [adjusted RR 0.65, 95% CI 0.51-0.83]) but not in nulliparous women (10.2% compared with 12.4% [adjusted RR 0.91, 95% CI 0.74-1.12]) parous.

Conclusion: In obese nulliparous women, attempted vaginal delivery was not associated with increased composite maternal or neonatal morbidity. In obese parous women, attempted vaginal delivery was associated with increased composite maternal morbidity and lower composite neonatal morbidity.

Level Of Evidence: II.