Vaginal misoprostol for induction of labour: a more effective agent than prostaglandin F2 alpha gel and prostaglandin E2 pessary.

OBJECTIVES

To compare labour outcome in women who had labour induced with PGF2 alpha gel, PGE2 vaginal pessary or misoprostol administered intravaginally or orally.

STUDY DESIGN

Unmasked randomised controlled trial.

SETTING

Department of Obstetrics and Gynaecology, University of Zimbabwe, Harare.

SUBJECTS

Women with a singleton foetus in cephalic presentation after 37 weeks gestation admitted for induction of labour who were randomised to prostaglandin F2 alpha gel (n = 76), prostaglandin E2 pessary (n = 75) and misoprostol administered either intra-vaginally (n = 128) or orally (n = 127).

MAIN OUTCOME MEASURES

Primary outcome was induction to delivery interval. Secondary outcomes included use of oxytocin during labour, mode of delivery, duration of labour, neonatal condition at delivery and maternal complications.

METHODS

Four hundred and six women admitted for induction of labour with a singleton foetus in cephalic presentation after 37 weeks gestation were enrolled. To estimate the risk with induction using other agents the odds ratio and 95% confidence interval was calculated using the group that received prostaglandin F2 alpha gel as referents.

RESULTS

The women were comparable for baseline characteristics. Compared to prostaglandin F2 alpha gel, the need for augmentation with oxytocin in labour was significantly reduced in women induced with prostaglandin E2 pessary (OR 0.46; 95%CI 0.23 to 0.93), vaginal misoprostol (OR 0.34; 95%CI 0.18 to 0.63) and oral misoprostol (OR 0.42; 95%CI 0.22 to 0.78). There was no difference in mode of delivery. There was a significantly reduced risk (OR 0.20; 95%CI 0.04 to 0.86) of Caesarean section (CS) for failure to progress in the vaginal misoprostol group. Labour induced with misoprostol and prostaglandin E2 pessary was significantly shorter than in prostaglandin F2 alpha gel. Vaginal misoprostol significantly shortened the induction to delivery interval. There were more admissions to the neonatal unit in the misoprostol groups.

CONCLUSION

Compared to prostaglandin F2 alpha gel, misoprostol and prostaglandin E2 pessary had reduced need for oxytocin and a shorter duration of labour. Effects of misoprostol on the foetus need further investigation before it is used as a routine agent for induction of labour.