InductionBMJ 1999; 318 doi: http://dx.doi.org/10.1136/bmj.318.7189.995 (Published 10 April 1999) Cite this as: BMJ 1999;318:995
- Geoffrey Chamberlain
- Luke Zander.
Labour is induced when an external agent is used to stimulate delivery before the onset of spontaneous labour. Induction must be distinguished clearly from augmentation of labour: both use similar techniques, but the first aims to start labour, whereas the second enhances uterine contractions once labour has started.
Induction is the stimulation of the uterus with the aim of starting labour to ensure delivery of the fetus at an appropriate time when the baby is thought to be safer outside the uterus than in it
No statutory national data are collected on the incidence of induction. The National Birthday Trust's study on home births in 1994 showed a 19% induction rate among a normal group of women who planned to deliver in hospital compared with 0.2% in those who delivered at home. Hospital reports, where published, vary from 0% to 30%.
Induction and augmentation
Induction means starting labour
Augmentation means enhancing a labour that has already started
There are few absolute indications for inducing labour, and priorities vary with the obstetrician. Postmaturity (when the pregnancy extends well beyond the expected delivery date) still heads the list, followed by suspected fetal growth retardation and maternal hypertension. Social factors—such as the woman's own wishes—play a larger part these days.
In a meta-analysis of 10 randomised controlled trials comparing induction at 41-42 weeks with conservative treatment, Crowley showed the increased risk of perinatal deaths associated with prolonged pregnancy. The risk is reduced by induction at 41 weeks (Cochrane Collaboration).
A non-medical indication for induction is the woman's own wishes. Many mothers exceeding their expected delivery date by a week consider that their pregnancy has gone far enough and ask for induction. Roberts and Young found that about 70% of women expressed the wish to be induced …