Efficacy of Oral Misoprostol Compared with Vaginal Dinoprostone for Cervical Ripening and Labor Induction

Objective: The study focuses on the pharmacological induction of labor and aims at comparing oral misoprostol (Cytotec®) with vaginal dinoprostone (slow-release vaginal insert Propess® and vaginal gel Prepidil®). Methods: A retrospective observational study was conducted. Through medical records review, we collected data on women at term with a singleton pregnancy who underwent labor induction at our tertiary care center, Sant'Anna Hospital of Turin, from January 2018 to January 2023. A total of 1230 were included: 446 received oral misoprostol and 784 received vaginal dinoprostone. The primary outcome was cesarean section rate. Maternal and neonatal secondary outcomes included: operative delivery rate, postpartum hemorrhage rate, induction-to-delivery interval, incidence of vaginal delivery within 12 and 24 hours, 1-minute and 5-minute Apgar Score. Results: The cesarean section rate was significantly lower in the oral misoprostol group compared to the vaginal dinoprostone group (OR 0.619, 95% CI 0.434, 0.883). The induction-to-delivery interval was significantly shorter in the group of patients who underwent induction with Cytotec® (median 16 hours, IQR 17) than in the group of patients who were induced with Prepidil® and/or Propess® (median 17 hours, IQR 18.2) (p < 0.001). There were no statistically significant differences in the other maternal and neonatal secondary outcomes. Within the subgroup of patients with pre-induction Bishop score > 3, the cesarean section rate was significantly lower in the group of women who underwent induction with Cytotec® than in the group of women induced with vaginal dinoprostone, with no statistically significant differences in the other maternal and neonatal outcomes (OR 0.466, 95% CI 0.232, 0.936). Within the subgroup of patients with pre-induction Bishop score ≤ 3, we found no statistically significant differences in cesarean section rate; however, the induction-to-delivery interval was significantly shorter (Cytotec®: median 19 hours, IQR 18; Prepidil® and/or Propess®: median 23.7 hours, IQR 24.9; p < 0.001) and the incidence of vaginal delivery within 24 hours was significantly higher (OR 1.461, 95% CI 1.050, 2.033) in the misoprostol group. Conclusion: Labor induction with oral misoprostol appears to be associated with a lower cesarean section rate and a shorter induction-to-delivery interval when compared to labor induction with vaginal dinoprostone. The decrease in cesarean section rate is even more noticeable in patients with favorable Bishop score. In patients with an unfavorable Bishop score, the induction-to-delivery interval appears to be shorter and the incidence of vaginal delivery within 24 hours is higher with the use of oral misoprostol.