Vaginal misoprostol for cervical ripening and induction of labour

Abstract

Background

Misoprostol (Cytotec, Searle) is a prostaglandin E1 analogue widely used for off‐label indications such as induction of abortion and of labour. This is one of a series of reviews of methods of cervical ripening and labour induction using standardised methodology.

Objectives

To determine the effects of vaginal misoprostol for third trimester cervical ripening or induction of labour.

Search methods

The Cochrane Pregnancy and Childbirth Group's Trials Register (November 2008) and bibliographies of relevant papers. We updated this search on 15 February 2012 and added the results to the awaiting classification section.

Selection criteria

Clinical trials comparing vaginal misoprostol used for third trimester cervical ripening or labour induction with placebo/no treatment or other methods listed above it on a predefined list of labour induction methods.

Data collection and analysis

We developed a strategy to deal with the large volume and complexity of trial data relating to labour induction. This involved a two‐stage method of data extraction.

We used fixed‐effect Mantel‐Haenszel meta‐analysis for combining dichotomous data.

If we identified substantial heterogeneity (I² greater than 50%), we used a random‐effects method.

Main results

We included 121 trials. The risk of bias must be kept in mind as only 13 trials were double blind.

Compared to placebo, misoprostol was associated with reduced failure to achieve vaginal delivery within 24 hours (average relative risk (RR) 0.51, 95% confidence interval (CI) 0.37 to 0.71). Uterine hyperstimulation, without fetal heart rate (FHR) changes, was increased (RR 3.52 95% CI 1.78 to 6.99).

Compared with vaginal prostaglandin E2, intracervical prostaglandin E2 and oxytocin, vaginal misoprostol was associated with less epidural analgesia use, fewer failures to achieve vaginal delivery within 24 hours and more uterine hyperstimulation. Compared with vaginal or intracervical prostaglandin E2, oxytocin augmentation was less common with misoprostol and meconium‐stained liquor more common.

Lower doses of misoprostol compared to higher doses were associated with more need for oxytocin augmentation and less uterine hyperstimulation, with and without FHR changes.

We found no information on women's views.

Authors' conclusions

Vaginal misoprostol in doses above 25 mcg four‐hourly was more effective than conventional methods of labour induction, but with more uterine hyperstimulation. Lower doses (25 mcg four‐hourly or less) were similar to conventional methods in effectiveness and risks. The authors request information on cases of uterine rupture known to readers. The vaginal route should not be researched further as another Cochrane review has shown that the oral route of administration is preferable to the vaginal route. Professional and governmental bodies should agree guidelines for the use of misoprostol, based on the best available evidence and local circumstances.

[Note: The 27 citations in the awaiting classification section of the review may alter the conclusions of the review once assessed.]

Plain language summary

Vaginal misoprostol is effective in inducing labour but more research is needed on safety

Sometimes it is necessary to bring on labour artificially because of safety concerns for the mother or baby. Misoprostol is a hormone given by insertion through the vagina or rectum, or by mouth to ripen the cervix and bring on labour. The review of 121 trials found that larger doses of misoprostol are more effective than prostaglandin and that oxytocin is used in addition less often. However, misoprostol also increases hyperstimulation of the uterus. With smaller doses, the results are similar to other methods. The trials reviewed are too small to determine whether the risk of rupture of the uterus is increased. More research is needed into the safety and best dosages of misoprostol. Another Cochrane review has shown that the oral route of administration is preferable to the vaginal route.