Misoprostol for labor induction in women at term with intact membranes and an unfavorable cervix: A systematic review

To evaluate the use of misoprostol, compared to prostaglandin E2(PGE2), for labor induction in women at term with an unfavorable cervix and intact membranes. MEDLINE, PubMed, EMBASE and the Cochrane Library were searched for human studies using the keywords “misoprostol” and “labor induction” identifying randomized trials that included women at term (≥37 wks) with intact membranes and unfavorable cervix, comparing misoprostol with PGE2 for labor induction. The primary analysis compared any misoprostol with any PGE2 for all women, with a subgroup analysis for nulliparous women. Secondary analyses compared different routes of misoprostol (oral or vaginal) and PGE2 (intracervical or vaginal). Meta-analyses were conducted where appropriate. Thirteen of 524 articles identified met the criteria for systematic review, with 3 providing information for nulliparous women. There was no difference in the risk of cesarean delivery between misoprostol and PGE2 groups (RR=0.98, 95%CI=0.82–1.17). Any misoprostol was associated with higher risks of tachysystole and hyperstimulation compared to any PGE2 (RR=1.86, 95%CI=1.01-3.43 and RR=3.88, 95%CI=2.04-7.37, respectively). There was a higher rate of vaginal delivery within 24 hours with any misoprostol compared to any PGE2 (RR=1.23, 95%CI=1.02-1.52) and a lower rate of oxytocin use (RR=0.70, 95%CI=0.57-0.86), but a trend toward increased meconium staining (RR=1.22, 95%CI=0.96-1.55). Among nulliparous women misoprostol use was associated with a lower rate of oxytocin use (RR=0.82, 95%CI=0.68-0.99), but a higher rate of NICU admission (RR=2.49, 95%CI=1.06-5.83). Although misoprostol in women at term with an unfavorable cervix and intact membranes is more effective than PGE2 in achieving vaginal delivery within 24 hours, misoprostol does not reduce the rate of cesarean delivery and it increases the rates of tachysystole and hyperstimulation. In the subgroup of nulliparous women misoprostol results in a higher rate of NICU admission. Further studies of low dose misoprostol (25 μg) in nulliparous women may be warranted.