The effect of vaginal pH on labor induction with vaginal misoprostol.
OBJECTIVE
To estimate the association of vaginal pH on the induction to vaginal delivery interval in labor induction with vaginal misoprostol.


METHODS
Women presenting at term with intact membranes for labor induction were recruited. The pH of the vagina was measured during a digital examination of the cervix to determine the Bishop Score. Labor was induced with 25 microg of vaginal misoprostol placed every 6 h until spontaneous rupture of membranes or active labor occurred. The primary outcome was the induction to vaginal delivery interval in the lower pH (< 5) versus higher pH (> or = 5) group. Secondary outcomes assessed maternal and neonatal morbidities. Sample size calculated a priori estimated 120 subjects were required for a power of 95% and a 2-tailed a of 0.05.


RESULTS
120 women met inclusion criteria and had available pH data. There was no difference in the induction to vaginal delivery interval in the lower pH (1455 min) versus higher pH group (1295 minutes, Mean difference 160 [- 147,468] P = .30). No difference was observed for operative delivery rates or neonatal outcomes.


CONCLUSIONS
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.
Chandra
S
S
Department of Obstetrics and Gynecology, Dalhousie University, Halifax, Nova Scotia, Canada. schandra@cha.ab.ca
Allen
Vm
V
Lee
W
W
Fanning
Ca
C
Young
Dc
D
D000282:Administration, Intravaginal; D000328:Adult; D015992:Body Mass Index; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007231:Infant, Newborn; D007751:Labor, Induced / Q000379:methods*; D016595:Misoprostol / Q000008:administration & dosage* / Q000009:adverse effects; D010120:Oxytocics / Q000008:administration & dosage* / Q000009:adverse effects; D011247:Pregnancy; D011256:Pregnancy Outcome; D014621:Vagina / Q000737:chemistry*
D010120:Oxytocics; D016595:Misoprostol