Objective: The objective of the study was to compare the effectiveness, safety, and side effects of low-dose oral misoprostol with vaginal dinoprostone for cervical ripening and labor induction.

Study Design: Women with Bishop score 6 or less admitted for labor induction at term were eligible for this randomized controlled trial. Exclusion criteria were multiple pregnancy, breech, fetal distress, or previous uterine scar. The allocation to the oral misoprostol group (20 μg given every 2 hours increased to 40 μg depending on uterine contractions) or to the vaginal dinoprostone group (2 mg twice, 6 hours apart) was contained in a sealed, opaque, and consecutively numbered envelope.

Results: Two hundred women (100 in each group) were included. The proportion of vaginal delivery within 24 hours was 56% in the misoprostol group and 62% in the dinoprostone group (relative risk 0.90, 95% CI 0.72-1.14). The risk of cesarean section was 18% and 19%, respectively. The median interval to delivery, calculated from survival analysis, was longer in the misoprostol group (1305 minutes) compared with the dinoprostone group (1080 minutes). The log-rank test was not significant (P = .35). Uterine hyperstimulation occurred in 9% of women in the misoprostol group compared with 14% in the dinoprostone group (P = .27). The only significant difference in neonatal outcomes was a more frequent presence of thick meconium in the misoprostol group (P = .03).

Conclusion: We found no difference in terms of effectiveness and safety between low-dose oral misoprostol and vaginal dinoprostone used for induction of labor. This regimen avoids the excessive uterine contractility noted in previous studies, where higher doses of misoprostol were administered at longer intervals.