Association between maternal BMI and success of labor induction with oral misoprostol: a cohort study

To evaluate the association between maternal obesity (BMI ≥ 30 kg/m²) and the success of labor induction with oral misoprostol. We conducted a retrospective cohort study including patients who underwent labor induction with oral misoprostol between 2017 and 2023 at a tertiary medical center. Outcomes were compared between women with obesity (BMI ≥ 30) and those without obesity (BMI < 30). The primary outcome was vaginal delivery within 24 h of induction. Secondary outcomes included mode of delivery, number of misoprostol doses, induction-to-delivery interval, and neonatal outcomes. Among 573 women induced with oral misoprostol, those with obesity had a lower rate of vaginal delivery within 24 h (63% vs. 72%, p = 0.021), whereas overall vaginal delivery rates were similar (85% vs. 89%, p = 0.11). Women with obesity were more likely to require ≥ 3 misoprostol doses (p < 0.001) and had a longer induction-to-delivery interval (median 21.6 vs. 15.6 h, log-rank p = 0.0017). In multivariable analysis, obesity (OR 0.63, 95% CI 0.42–0.95), nulliparity, and higher birthweight were associated with reduced odds of vaginal delivery within 24 h. Neonatal outcomes were comparable between BMI groups. Maternal obesity is associated with lower odds of vaginal delivery within 24 h following induction with oral misoprostol, longer induction-to-delivery intervals, and greater dosing requirements. These findings support the need for further research into BMI-tailored induction protocols.