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Recording

Oral Plenary Session II - Fellows Plenary and Late-Breaking

Oral Plenary Sessions

(10) Optimal Misoprostol Dosing Among Patients with a BMI Greater Than 30: A Randomized Controlled Trial

Tuesday, February 13, 2024

8:15 AM – 8:30 AM

Location: Potomac Ballroom, Ballroom Level

Primary & Presenting Author(s)

Alexander M. Saucedo, MD

MFM Fellow
University of Texas at Austin, Dell Medical School
Austin, TX, United States

Coauthor(s)

MA

Miriam Alvarez, PhD

University of Texas at Austin, Dell Medical School
Austin, TX, United States
GM

George A. Macones, MD, MSCE

The University of Texas at Austin
Austin, TX, United States
Alison G. Cahill, MD

Professor
University of Texas at Austin, Dell Medical School
Austin, TX, United States
Lorie M. Harper, MD, MSCI (she/her/hers)

Associate Professor
University of Texas at Austin, Dell Medical School
Austin, TX, United States

Disclosure(s): I have no relevant financial relationships to report.

Objective: Patients with obesity have longer lengths of labor with increased risk of perinatal morbidity. It is unclear whether the same dose of misoprostol should be used for induction of labor in obese compared to non-obese women. We aimed to determine if 50mcg (compared to 25mcg) of vaginal misoprostol reduces the time from induction start to delivery in obese patients.

Study Design: Double-blinded, pragmatic randomized controlled trial, between June 2022, and July 2023. Patients with a BMI ≥ 30 kg/m² undergoing labor induction ≥ 36 weeks, singleton gestations, and a cervical dilation ≤ 3cm on admission, were included. Patients were randomized to 25 or 50 mcg of vaginal misoprostol. The primary outcome was time from induction to delivery. A priori, we estimated 90 subjects per group (N=180). This is based on 18 +/- 6 hours for time to delivery in the control (25mcg), alpha of 5%, and an 85% power to detect a 3-hour difference. Analysis was intention-to-treat. A two-sample t-test was used for the primary outcome, Cohen’s d as a measure of effect, and P values were reported. Logistic regression was used to analyze secondary outcomes.

Results: Of the 180 patients, 88 were assigned to the 25mcg group and 92 were assigned to the 50mcg group. Baseline characteristics were similar between groups. No difference was found in the primary outcome of time to delivery (21.59 hrs vs. 18.56 hrs; d = 0.28; 95% CI, -0.02-0.57). In a planned subgroup analysis, multiparous patients delivered faster in the 50mcg group (15.19 hrs. vs. 11.97 hrs; d = 0.51; 95% CI, 0.04-0.97). The rate of tachysystole was rare overall (2.2%) and non-significant between groups. No differences in maternal or neonatal adverse effects were observed.

Conclusion: Obese patients undergoing cervical ripening with 50mcg of vaginal misoprostol experienced similar time to delivery when compared to 25mcg. However, multiparous patients had a significantly reduced time to delivery when 50mcg was used. A higher dose of misoprostol may be a promising intervention for reducing time in labor by an average of 3 hours which warrants further study.