Misoprostol for labor induction: an alternative to Dinoprostone? A retrospective observational study

Background Misoprostol and dinoprostone are established agents for labor induction. Evidence on their comparative efficacy is inconclusive, and few studies have assessed the more stable tablet formulation of misoprostol. The primary objective was to compare induction-to-delivery time between misoprostol and dinoprostone. Secondary objectives were to assess induction-to-labor interval, need for a second method, and obstetric and neonatal outcomes. Methods We conducted a retrospective observational study between September 2021 and December 2024. Inclusion criteria were singleton term pregnancies undergoing labor induction during the study period with either misoprostol—25 mcg or 50 mcg tablets (Group 1)—or dinoprostone—1 or 2 mg gel or 10 mg pessary (Group 2)—and a Bishop score < 7. Results A total of 873 patients were included: 528 in Group 1 and 345 in Group 2. A robust double analysis was applied to balance age, gestational age, Bishop score at baseline, and parity, aiming to mitigate the potential influence of baseline differences between the groups. No significant differences were found in induction-to-delivery time (p = 0.710) or time from induction to active labor (p = 0.652). However, Group 1 had a significantly higher likelihood of vaginal delivery (OR = 1.38; 95% CI: 1.10–1.73; p = 0.004) and, was associated with a lower risk of postpartum hemorrhage (OR = 0.58; 95% CI: 0.46–0.73; p < 0.001). Conclusions Induction-to-delivery time did not differ significantly between methods. Oral misoprostol yielded higher vaginal delivery rates and lower postpartum hemorrhage than vaginal dinoprostone. Fetal outcomes were comparable, indicating similar neonatal safety. The study was approved by the Institutional Review Board on November 20, 2023 (IRB Protocol No. 240/2023).