Vaginal prostaglandins are a safe and effective way of bringing on labour. The use of these medications is not associated with an increase in operative deliveries. Prostaglandins are produced naturally by the body. They are involved in ripening the cervix and bringing on labour. Safety concerns for the mother or baby sometimes make it necessary to bring on labour artificially. Synthetic prostaglandins can be used and are available as vaginal tablets, gels, suppositories and pessaries. The induction regimens with number of applications, dosages, and time intervals between doses vary considerably. Sustained release pessaries reduce the number of applications needed and so the number of vaginal examinations.
This review set out to determine the effectiveness and safety of vaginal prostaglandins for third trimester cervical ripening and induction of labour in comparison with placebo or no treatment, or other vaginal prostaglandins (except misoprostol). We identified 63 randomised controlled studies involving a total of 10,441 women. Vaginal prostaglandin E2 is an effective induction agent as it increases the likelihood of vaginal birth within 24 hours with no evidence of an effect on the rate of caesarean section. Requirements for oxytocin augmentation were reduced. Prostaglandin E2 tablets, gels, or pessaries appear to be as effective as each other. Sustained release inserts were associated with a reduction in instrumental vaginal deliveries compared to vaginal PGE2 gel or tablet, an effect that was greater in women with an unfavourable cervix. Comparing vaginal prostaglandin E2 to placebo or no treatment, the risk of uterine hyperstimulation with fetal heart rate changes was increased. Sustained release pessaries were associated with trends of increased hyperstimulation, with and without fetal heart rate changes, compared to gel or tablets. Lower dose regimens, as defined in the review, appear as efficacious as higher dose regimens.
Very limited data were available in the included trials on time in labour and patient satisfaction. Few studies have addressed issues relating to the safety of using vaginal prostaglandins for induction of labour as an outpatient.