Impact of Introducing a Controlled-Release Dinoprostone Vaginal Insert for Labor Induction: A Retrospective...

Cervical ripening is commonly performed before oxytocin administration during labor induction in pregnant women with an unfavorable cervix. In Japan, a controlled-release Dinoprostone vaginal insert (CR-DVI) was approved in 2020. Although many studies have compared the mechanical methods of ripening and prostaglandins, few have examined the impact of additional options for labor induction. This study aimed to assess the impact of CR-DVI as an additional option for labor induction in women with an unfavorable cervix.

In this single-center retrospective study conducted in Japan, 265 participants were divided into two groups: before (January 2018 to May 2020) and after (June 2020 to November 2022) CR-DVI introduction. Before CR-DVI was introduced, hygroscopic dilators were used for all cases instead. On the other hand, after the introduction of CR-DVI, the first choice for cervical ripening was CR-DVI. The CR-DVI was retained vaginally for up to 12 hours after insertion. However, if hyper-stimulation or non-reassuring fetal status was suspected, or if a new membrane rupture occurred, it was removed immediately according to the removal criteria. Oxytocin infusions were used during both periods if needed. We compared delivery and neonatal outcomes between the groups.

The 265 participants were divided into two groups: before (n=116) and after (n=149) CR-DVI introduction. There were no significant differences in maternal characteristics except for the primiparous proportion. CR-DVI was used in 93% of cases after introduction. Hygroscopic dilators also continued to be used; however, their use decreased to about 34%. The vaginal delivery rate was significantly higher after the introduction of CR-DVI than before its introduction (50.9% vs. 66.4%; p=0.01). Multivariable analysis revealed a significantly higher rate of vaginal delivery after CR-DVI introduction. Of the 149 cases in which a CR-DVI was used, 111 (79.9%) were removed before 12 hours. There were no significant differences in neonatal outcomes.

The rate of vaginal delivery was higher after CR-DVI introduction than before its introduction, and adverse pregnancy outcomes did not increase. Therefore, introducing CR-DVI as an option for labor induction may increase the probability of vaginal delivery. Safety can also be ensured by adhering to the removal criteria.