The effect of vaginal pH on labor induction with vaginal misoprostol

Abstract

The pH of the vagina may not affect the length of the induction to vaginal delivery interval in women undergoing labor induction with vaginal misoprostol. Further research is required to determine factors that may influence the efficacy of vaginal misoprostol when used for labor induction.

Effect of vaginal pH on the efficacy of vaginal misoprostol for induction of midtrimester abortion

“…Furthermore, the presence of a low vaginal pH was associated with a lower total dose and the number of doses of misoprostol, along with the decreased incidence of fever or severe abdominal pain with subsequent lower dosage of analgesics. The efficacy of intravaginally administered misoprostol for cervical ripening and labor induction has been previously examined in relation to vaginal pH 29–31 . Our findings are in accordance with those of other investigators who used misoprostol 50 μg/4 h for a maximum of three doses in 103 women until either the spontaneous rupture of the membranes or active labor occurred.…”

“…They reported that all women with a vaginal pH < 5 reached the active phase of labor, being significantly different from 87% in patients with a vaginal pH ≥ 5, with delivery within 12 hours in 59.6% and 23.3%, respectively 29 . The efficacy of the drug, however, was found not to be related to the presence of a vaginal pH < 5 in another two studies 30,31 . Differences in the dosage of misoprostol might explain these contradictory results.…”

“…There were no published reports on which to base the sample size calculation. Each of the largest two studies in this respect comprised more than 100 patients 29,31 . So, in the present study, we recruited 110 women in total.…”

“…In some of these studies, though vaginal pH of the patients was not measured, it was recognized as an important factor, deserving evaluation 12,15,28 . Some investigators examined the efficacy of intravaginally administered misoprostol for cervical ripening and labor induction in relation to vaginal acidity; however, with contradictory results 29–31 . The purpose of this investigation was to evaluate the influence of vaginal pH on the efficacy and side‐effects of misoprostol for the induction of midtrimester abortion.…”

The Effect of Vaginal pH on the Efficacy of Vaginal Misoprostol for the Induction of Midtrimester Pregnancy Termination

“…The average time from the start of the Induction to the expulsion of the fetus was not significantly different between the both groups at 24 hours and 48 hours. This is consistent with other studies that used vaginal misoprostol for the induction of labour (8,10). There was, also, no correlation between the vaginal pH and the duration and outcome with the induction of labour in these studies.…”