Objective
To examine rates of attempted and successful vacuum-assisted vaginal delivery by pre-pregnancy body mass index (BMI).
Methods
We conducted a retrospective cohort study of 2,084 women with singleton gestations needing operative delivery assistance and vacuum-eligible (fully dilated, ≥ +2 station, ≥34 weeks) using 2006–2014 in-patient records. Pre-pregnancy BMI was categorized as underweight (<18.5kg/m2), normal weight (18.5kg/m2≤BMI<25kg/m2), overweight (25kg/m2≤ BMI<30kg/m2), or obese (≥30kg/m2). Logistic regression models estimated odds ratios (ORs) and 95% confidence intervals (CIs) of attempted and successful vacuum-assisted vaginal delivery by pre-pregnancy BMI adjusted for age, race, marital status, parity, diabetes, labor induction–augmentation, episiotomy, gestational age, and infant birth weight.
Results
Thirty-nine percent of women requiring delivery assistance and eligible for a vacuum were overweight or obese, 79% had vacuum attempts, and 95.3% of attempted vacuum-assisted vaginal deliveries were successful. Compared to women who were normal weight pre-pregnancy (82.8%), women who were overweight or obese were less likely to have vacuum attempted (75.8%, OR=0.71, 95% CI 0.53–0.96 and 71.2%, OR=0.53, 95% CI 0.39–0.74, respectively). Among women with attempted vacuum-assisted vaginal delivery, successful delivery did not differ by pre-pregnancy BMI (92.6%, OR=0.54, 95% CI 0.21–1.37 for underweight; 94.5%, OR=1.07, 95% CI 0.57–2.00 for overweight; 96.3%, OR=1.09, 95% CI 0.51–2.33 for obese, versus 95.6% among normal weight women).
Conclusions
Among women in need of operative delivery assistance, pre-pregnancy obesity was associated with lower likelihood of attempted vacuum-assisted vaginal delivery, but if attempted, success rates were similar to rates among normal weight women. With significant morbidity of second stage cesarean delivery in obese women, research should examine whether vacuum-assisted vaginal delivery may be appropriate for additional obese patients.