Oral misoprostol for induction of labour with a viable fetus

Misoprostol is a synthetic prostaglandin which has been used to induce labour. Oral use of the drug misoprostol may be convenient, but an overdose could cause uterine hyperstimulation and precipitate labour which may be life-threatening for both mother and fetus.

The objective of this review was to assess the effects of oral misoprostol used for labour induction in women with a viable fetus.

We searched the Cochrane Pregnancy and Childbirth Group trials register and the Cochrane Controlled Trials Register.

Randomised trials of oral misoprostol versus any other method, placebo or no treatment given to women with a viable fetus for induction of labour.

The selection of trials and data extraction were undertaken by one reviewer and independently checked by two other reviewers.

Five trials were included. In one placebo trial, oral misoprostol reduced the need for oxytocin infusion and shortened delivery time in women with prelabour rupture of membranes at term. In another trial, compared to vaginal prostaglandins, oral misoprostol reduced the need for oxytocin (relative risk 0.62, 95% confidence interval 0.47 to 0.82). Based on two trials, the caesarean section rate with oral misoprostol was 20. 2% (55/272) compared with 15.5% (42/270) for vaginal prostaglandins (relative risk 1.29, 95% confidence interval 0.90 to 1.86). Different doses (100 micrograms three hourly and 200 micrograms six hourly) were used in the two trials that compared oral with vaginal misoprostol. The caesarean section rate was 21.8% in the oral misoprostol group compared with 13.5% for vaginal misoprostol (relative risk 1.62, 95% confidence interval 0.85 to 3.09). The uterine hyperstimulation rate with oral misoprostol was 37.5% (36/96) compared with 28% (25/89) for vaginal misoprostol (relative risk 1.32, 95% confidence interval 0.86 to 2.04). There was significant heterogeneity between these two trials.

Oral misoprostol may be an effective method for labour induction. However clinically effective oral regimens may have an unacceptably high incidence of uterine hyperstimulation and possibly uterine rupture.