(673) Mechanical cervical ripening among patients with a BMI greater than 30

Objective: Patients with obesity undergoing induction of labor (IOL) are at an increased risk for a prolonged labor duration. The efficacy of a combination of a cervical ripening balloon (CRB) plus vaginal misoprostol (VM) in this population is not well described. We aimed to determine the effect of CRB + VM versus VM alone on time from IOL to delivery in patients with obesity.

Study Design: Secondary analysis of a single center, double-blinded RCT between 6/2022 and 7/2023, which randomized near-term, singleton gestations with a BMI ≥ 30 kg/m² undergoing IOL, with a cervical dilation ≤ 3cm, to either 25mcg or 50mcg of VM. For this analysis, we included only those patients from the primary study who received a CRB +VM upon induction initiation and compared them to those patients receiving only VM. The primary outcome was time from induction initiation to delivery. Multivariable linear regression was used for the primary outcome with adjustments made for randomization group, nulliparity, and cervical dilation on admission.

Results: This secondary analysis included 125 participants: 55 (44%) receiving CRB + VM versus 70 (56%) receiving VM alone. Baseline characteristics were similar, however those with a CRB were younger (26.2 years vs. 29.1 years; p=0.03) and with fewer Hispanic patients (69.1% vs. 82.9%; p=0.04). 65 (52%) patients received the 50mcg dose versus 60 (48%) received the 25mcg dose which was used as a covariate in our final model. Following adjustment, patients with a CRB+VM had a reduced time to delivery (14.7 hrs vs. 17.7 hrs; p=0.02) and reduced time to active labor (11.8 hrs vs. 14.6 hrs; p=0.02). No differences in cesarean delivery or adverse maternal/neonatal outcomes were seen.

Conclusion: In patients with obesity undergoing IOL, a combination of CRB+VM reduced time to delivery and active labor by an average of 3 hours. Given this population’s increased risk for prolonged delivery times and perinatal morbidity, a combination of mechanical dilation with misoprostol administration should be considered.