The risk of a cesarean delivery was 12% lower in women whose labour was induced compared with women who were managed with a "wait-and-see" approach (expectant management), according to a research paper published in CMAJ (Canadian Medical Association Journal).
Labour is induced in about 20% of all births for a variety of reasons such as preeclampsia, diabetes, preterm rupture of the membranes, overdue pregnancy and fetal distress. Induction is often thought to be associated with increased risk of cesarean deliveries despite evidence indicating a lower risk. However, much of this evidence is weak.
Researchers undertook a systematic review and analysis of 157 randomized controlled trials that included 31 085 deliveries to determine whether there is an increased risk of cesarean delivery associated with induction compared with expectant management.
"The risk of cesarean delivery following labour induction was significantly lower than the risk associated with expectant management," writes Professor Khalid Khan, Queen Mary University of London, London, United Kingdom, with coauthors. "This finding supports evidence from systematic reviews but is contrary to prevalent beliefs and information from consumer organizations, guidelines and textbooks."
The authors found a 12% lower risk of cesarean delivery in term or post-term pregnancies that were induced but not in preterm births. The risk was lower in both high-risk and low-risk pregnancies, and the risk of fetal death or complications was lower in women who were induced compared with those managed expectantly.
"These findings show that induction is a way to increase the likelihood of a vaginal birth," states Professor Khan.
Prostaglandin E2, commonly used in the UK, Canada and the United States to induce labour, was associated with significant reductions in the risk of cesarean delivery. However, oxytocin and amniotomy, also widely used, did not show a decreased risk of cesarean delivery.
"Our meta-analysis has provided a robust answer to the disputed question of risk of cesarean delivery associated with induction of labour. Women whose labour was induced were less likely than those managed expectantly to have a cesarean delivery. In addition, the risk of fetal death and admission to neonatal intensive care unit were decreased in the induction group," the authors conclude.
They note that this evidence may have clinical practice implications by helping physicians determine who should be induced and in explaining the risks of induction.