Dinoprostone vaginal insert demonstrates 30.7% C-section rate and general safety for labor induction in real-world Japanese data.

Inducing labor for an unfavorable cervix (Bishop score ≤7) often requires effective cervical ripening agents. While dinoprostone (prostaglandin E2) is a well-established method, real-world data on its utilization patterns, safety, and delivery outcomes, especially after its recent introduction in specific regions like Japan, are crucial. Understanding these real-world metrics helps clinicians optimize protocols and manage patient expectations, addressing gaps left by controlled clinical trials regarding diverse patient populations and combined ripening strategies.

This two-stage nationwide, multicenter survey targeted 690 certified Japanese obstetrics and gynecology training institutions. Researchers collected clinical data for up to 25 consecutive cases per institution, where labor was induced with the dinoprostone vaginal insert between January and December 2021. A total of 973 registered cases (947 eligible for analysis) were included. Primary endpoints included utilization patterns, delivery outcomes (e.g., cesarean section rate, induction-to-delivery interval), and adverse events (e.g., uterine tachysystole, fetal heart rate abnormalities). Subgroup analyses compared nulliparous women receiving the insert alone (P) versus those requiring subsequent mechanical ripening (P to M), and those receiving mechanical ripening before the insert (M to P) versus the insert first (P to M).

The study analyzed 947 eligible cases from 69 institutions, with nulliparous women accounting for 74.8%. The overall cesarean section rate was 30.7%, specifically 36.3% in nulliparas and 14.2% in multiparas. The median time from dinoprostone vaginal insert initiation to delivery was 31.6 hours. Safety data revealed uterine tachysystole in 18.1% of cases and fetal heart rate abnormalities in 15.8%, though timely management prevented serious outcomes.

In nulliparous subgroup analyses, those ripened with the insert alone (P) demonstrated significantly shorter induction-to-delivery intervals, lower cesarean rates, and reduced oxytocin use compared to those requiring subsequent mechanical ripening (P to M), despite experiencing more tachysystole.

Among cases requiring both ripening methods, the order of techniques (M to P vs. P to M) did not significantly affect the success rate of vaginal delivery.