Effect of vaginal pH on efficacy of dinoprostone gel for labour induction

Abstract

Background: Induction of labour is defined as an intervention designed to artificially initiate uterine contractions leading to progressive dilatation and effacement of the cervix and birth of the baby. The aim of the study was to evaluate the influence of vaginal pH on the efficacy of dinoprostone gel for labor induction. Methods: A prospective study conducted on 200 subjects within 1 year in India. The Bishop score and vaginal pH (with pH paper, Sigma Chemical Company, St. Louis, USA) of subjects undergoing induction of labor with dinoprostone gel was assessed prior induction. After 6 hours of induction, PGE2 gel was repeated or labor was augmented. The vaginal pH measured was compared with age, parity, Bishop Score, time to enter into active phase of labor, and the mode of delivery. The significance of association was calculated by Chi-square test. Results: Majority subjects had pH in the range 5-6.Subjects with higher parity were associated with higher vaginal ph. Higher vaginal pH was associated with a higher Bishop score prior to induction, responded to single induction, and had a higher number of vaginal deliveries than those with lower vaginal pH. There was no significant association found in vaginal pH and the time taken to enter into active phase of labor. Subjects with pregnancy induced hypertension were found to have higher vaginal ph. Conclusions: Parity influences vaginal pH and vaginal pH itself has a significant effect on the Bishop Score prior induction. Hence knowing the vaginal pH prior induction could be a useful tool to assess the labor outcome in induction with PGE2. Keywords: