Induced labour has an impact on the birth experience of women. It may be less efficient and is usually more painful than spontaneous labour, and epidural analgesia and assisted delivery are more likely to be required.
Induction of labour is a relatively common procedure. In 2012−2013, more than 1 in 5 deliveries in England were induced (Health and Social Care Information Centre 2013). The NICE clinical guideline on induction of labour notes that, in 2004−2005, when labour was induced using pharmacological methods (whether or not surgical induction was also attempted), less than two-thirds of women gave birth without further intervention, and about 15% of women had instrumental births and 22% had emergency caesarean sections. Induction of labour has a large impact on the health of women and their babies and so needs to be clearly clinically justified.
The NICE clinical guideline on induction of labour was published in 2008. It states that, if induction of labour is clinically justified, vaginal prostaglandin E2 (dinoprostone) is the preferred method, unless there are specific clinical reasons for not using it (in particular the risk of uterine hyperstimulation). It should be administered as a gel, tablet or controlled-release vaginal insert. Costs may vary over time, and trusts and units should take this into consideration when prescribing vaginal prostaglandin E2.
The 2008 NICE guideline states that misoprostol (a prostaglandin E1) should be offered (off label) as a method of induction of labour only to women who have had an intrauterine fetal death (see also the evidence summary on Induction of labour in late intrauterine fetal death - vaginal misoprostol [after oral mifepristone]) or in the context of a clinical trial.
The Guideline Development Group for the NICE guideline considered the evidence for misoprostol for the induction of labour and concluded that vaginal misoprostol 25 micrograms was not superior to vaginal prostaglandin E2 in women with an undefined, variable and unfavourable cervix. (An unfavourable cervix suggests that spontaneous onset of labour is unlikely. The cervix is long and firm in consistency and must be made softer and shorter to allow labour to begin.) Doses of misoprostol above 25 micrograms were associated with higher rates of successful induction of labour but at the expense of higher rates of uterine hyperstimulation. In women with a favourable cervix, there was not enough data comparing the efficacy and safety of vaginal misoprostol with other regimens to reach any conclusions.
In November 2013, a UK marketing authorisation was granted for the misoprostol controlled-release vaginal delivery system (Mysodelle) for the induction of labour in women with an unfavourable cervix, from 36 weeks' gestation, in whom induction is clinically indicated. The manufacturer has advised that the UK launch is expected in quarter 4, 2014 (Ferring Pharmaceuticals: personal communication, January 2014).
Currently, only short-acting oral preparations of misoprostol are available and none of these is licensed for the induction of labour in the UK. In practice, oral misoprostol tablets are sometimes administered vaginally to induce labour. Tablets must be cut or made into suspension to achieve lower doses but uniform concentration and accurate drug delivery is not guaranteed. Use of the oral tablets in this way is off-label. In line with guidance from the General Medical Council (GMC), it is the responsibility of the prescriber to determine the clinical need of the patient and the suitability of using misoprostol outside its authorised indications.