Effect of acidic vaginal pH on the efficacy of dinoprostone (PGE2) vaginal tablet for labor induction in full term pregnant women: a randomized controlled trial.

Objectives: There is controversial evidence that acidification of vaginal pH may increase the efficacy of vaginal prostaglandins in labor induction, with research being mainly focused on misoprostol. This study aims to evaluate the impact of this intervention on the progress of labor induction with dinoprostone (PGE2) vaginal tablet.

Methods: This double-blind, parallel-group, randomized study was conducted between October 2021 and December 2022 at Alexandra General Hospital, Athens, Greece. A total of 230 women with singleton, full term pregnancy that were scheduled for labor induction were randomly divided into two groups: Group A, who received acidic vaginal wash (5 % acetic acid) and Group B, who received a normal saline vaginal wash. Afterwards, participants received a vaginal tablet of 3 mg dinoprostone every 6 h (maximum two doses).

Results: There were no statistically significant differences in mode of delivery, duration of different labor stages, Bishop score changes and possible complications. Participants in the acidification group needed less often labor augmentation with oxytocin and epidural anesthesia (p=0.03).

Conclusions: Vaginal acidification seems to have no effect on the efficacy of the dinoprostone vaginal tablet. Even though it may reduce the need for oxytocin augmentation, there is no apparent benefit on clinical outcomes, such as reduction in cesarean section rates or shorter labor duration. Future research is necessary in order to validate these findings.