How Effective Is Cervical Ripening Using the Controlled-Release Dinoprostone Vaginal Delivery System for Primiparas with Unruptured Membranes?

Background: Labor induction has a low success rate, especially in primiparas with unruptured membranes. Previous studies focused on pregnant women with unruptured membranes, but none specifically targeted primiparas. Aims: To compare the effectiveness of a controlled-release dinoprostone vaginal delivery system for cervical dilatation (PROPESS) with that of mechanical dilation for labor induction in primiparous women with unruptured membranes. Materials and Methods: We retrospectively analyzed the data of 90 primiparas with unruptured membranes (41 and 49 in the PROPESS and mechanical dilation groups, respectively). The primary outcome was the cesarean section (CS) rate. The secondary outcomes were the prevalence of vaginal delivery within 12 or 24 h after the initial insertion, oxytocin usage rate, chorioamnionitis, additional use of mechanical dilation in the PROPESS group, and neonatal outcomes. Results: The CS rate was significantly lower in the PROPESS group than in the mechanical dilation group (p = 0.02). A total of 13 patients (31.7%) delivered within 24 h with PROPESS alone, indicating a significantly higher rate of delivery within 24 h in the PROPESS group (p = 0.02). Fewer patients required additional oxytocin in the PROPESS group than in the mechanical dilation group (p = 0.001). However, 14 (34%) patients in the PROPESS group required additional mechanical cervical dilation, resulting in a longer time to delivery than mechanical dilation. Conclusions: PROPESS significantly reduced CS rates and increased delivery rates 24 h after the initial insertion in primiparas with unruptured membranes compared to mechanical dilatation. However, failure to respond to PROPESS resulted in an overall longer delivery time than that of the conventional mechanical dilation group; therefore, identifying predictors of response to PROPESS is necessary.