This retrospective study aimed to compare the safety and efficacy of Prostin E2 and Propess for the induction of labor (IOL) in nulliparous women between January 2018 and October 2021. The inclusion criteria were nulliparous, singleton, >37 weeks’ gestation, cephalic presentation with an unfavorable cervix (Bishop score ≤ 6), no signs of labor, and use of one form of dinoprostone (Prostin E2 or Propess) for IOL. The cesarean section (C/S) rate and induction-to-birth interval were the main outcome measures. In total, 120 women were recruited. Sixty (50%) patients received Propess and 60 (50%) received repeated doses of Prostin E2. The Prostin E2 and Propess groups had similar patient characteristics, but the Bishop score was significantly higher in the Propess group than in the Prostin E2 group; therefore, multivariate analysis was conducted, and the Bishop score was not associated with the induction-to-birth interval. The C/S rate was not significantly different between the two groups, but the Propess group achieved a shorter induction-to-birth interval, a higher rate of vaginal delivery in 24 h, and a lower number of vaginal examinations than the Prostin E2 group. Propess was effective and safe in IOL and could be an option for cervical ripening in nulliparous pregnancy.

Background and Objectives: For many patients, the induction-to-delivery interval is shorter with Propess than with Prostin E2. However, some patients also require Prostin E2 to sufficiently boost their dinoprostone levels to achieve cervical change and vaginal delivery. In this study, we compared the efficacy of different timings of Prostin E2 administration after Propess use. Materials and Methods: This single-institution retrospective cohort study was conducted between January 2020 and August 2023. The inclusion criterion was an unfavorable cervix (Bishop score ≤ 6) after Propess use for 8 h. We divided the patients into three groups based on the addition of Prostin E2 at the 8th (group 1), 12th (group 2), and 24th (group 3) hour after Propess insertion. The primary outcome was the cesarean section rate. The secondary outcomes were the induction-to-birth interval, Bishop score at 24 h, neonatal outcomes, and the predictors of labor induction duration. Results: A total of 63 patients were analyzed across three groups based on the timing of Prostin E2 administration (8, 12, and 24 h). The gestational age differed significantly between groups (p < 0.001), with the highest age being observed in the 24 h group. The 8 h group had the shortest induction-to-birth interval (p < 0.001) and the highest Bishop scores after 24 h of Propess use (p < 0.001). Blood loss was lowest in the 12 h group (p = 0.027). No significant differences were found in relation to the mode of birth, tachysystole, neonatal birth weight, or Apgar scores. A multivariable analysis identified gestational age (β = 3.33; p = 0.015) and Bishop score after 24 h of PGE2 (β = −1.99; p < 0.001) as being independent predictors of labor duration. Conclusions: administering Prostin E2 to patients who had a poor response after Propess use was safe; additionally, adding it at the 8th hour after Propess initiation could result in a shorter induction-to-birth interval.