The evidence about induction was gathered from four studies: two systematic reviews looked at a wide range of trials and worked out the balance of the evidence, and two randomised controlled trials tested the impact that induction makes for particular groups of patients.
A review that looked at induction of labour at 41 weeks or more among low-risk women of any age found that inducing labour after the due date slightly lowers the risk of stillbirth or infant death soon after birth, compared with waiting for labour to start naturally. But the overall risk is low. The review also found that induction may reduce admissions to neonatal intensive care units. It reduces the likelihood of caesarean section but may slightly increase the chance of needing an assisted vaginal birth (for example, using forceps or vacuum extraction).
Focusing on the experience of women having their first baby at the age of 35 years or more, a trial found that having labour induced (rather than waiting for it to start naturally) did not increase the rate of caesarean section and that induction had no adverse short-term effects on outcomes for the women or their newborn babies - it had been thought that inducing labour might increase the rate of caesarean section.
A study conducted in the U.S. compared the outcomes for low-risk first time mothers of any age who had their labour induced at 39 weeks with those who waited for it to start naturally. It found that induction of labour at 39 weeks of pregnancy, as compared with expectant management, did not significantly reduce the frequency of problems in newborn babies, but did significantly reduce the rate of caesarean section. Mothers’ age did not make a significant difference to the results.
Of the various methods that can be used to induce labour, one systematic review found that misoprostol and, for women with favourable cervix, oxytocin with amniotomy (artificial rupture of membranes) appear to be more successful than other methods in achieving vaginal delivery within 24 hours. But the same review pointed out that what is less clear is how safe different methods are in terms of the risk of caesarean section, instrumental delivery such as forceps or ventouse, too-strong uterine contractions, admission to neonatal care unit and the newborn baby’s Apgar score.
What might this mean for a woman considering induction of labour?
Overall, the evidence from these studies suggests that having your labour induced may increase the likelihood of having an instrumental delivery but may also reduce the likelihood of having a caesarean section. It appears that inducing labour has no marked effect on the rate of problems occurring in newborn babies.
This section on Induction forms part of our Highlight on the Management of Labour which takes an evidence-based look at induction, pain relief, waterbirth and more . To read the Highlight in full click here.