Should all pregnant women be routinely offered induction of labour at 39 weeks? Although many women would prefer to wait for spontaneous labour, new research suggests being induced would substantially reduce their likelihood of requiring caesarean and could also be safer for the baby.

A multicenter US study published in the New England Journal of Medicine this month randomised 6,106 low-risk nulliparous women to either labour induction at 39 weeks or expectant management.

The relative risk of perinatal death or severe neonatal complications (the primary composite outcome) was 20% lower in the induction group than in the expectant management group (95% CI 0.64-1.00; p=0.049), the study found.*

The authors stated: “Labour induction is probably not associated with a higher risk of adverse perinatal outcomes than expectant management, and it may be associated with as much as a 36% lower risk than expectant management.”

Induction of labour was associated with a significantly lower frequency of caesarean delivery (18.6% versus 22.2%) and hypertensive disorders (9.1% versus 14.1%) compared with expectant management.

The authors wrote: “One caesarean delivery may be avoided for every 28 deliveries among low-risk nulliparous women who plan to undergo elective induction of labour at 39 weeks.”

Nevertheless, recruiting participants to the study was a major challenge, with only 27% of eligible women consenting to take part. Participants were younger than the average woman giving birth in the US, and also more likely to be African American or Hispanic.

An accompanying editorial said the recruiting problem was likely to reflect “deference to a perceived public preference for a less interventionist approach to the management of healthy pregnancies at full term.”

Dr Michael Gannon, former AMA president and a WA obstetrician has previously argued that routine induction at 39 or 40 weeks could reduce stillbirths and caesareans.

He told doctorportal: “One of the myths we have been trying to overcome is the notion that if you induce labour, you increase the rate of caesareans. This well-designed study shows that the very opposite is true.”

Dr Gannon said the induction of labour at 39-40 weeks should be discussed with all patients. Further, it should be offered and even recommended on a more regular basis.

“This evidence is completely at odds with the practice at a majority of public hospitals in Australia,” he said. “Private hospitals are often criticised for their higher rates of induction of labour, but scratch a bit deeper and the evidence shows why obstetricians are recommending it.”

He continued: “Whether women are giving birth in public hospitals or private hospitals, the city or the country, whether they are English speaking or not, they should be receiving the same evidence-based information that induction at 39-40 weeks reduces the requirement for caesarean and the risk of stillbirth.”

Dr Gannon acknowledged there would be “huge resource allocation issues” involved in increasing the induction rate. It would also likely precipitate an increase in epidurals.

He said the decision to induce at 39-40 weeks should take into account whether the woman’s cervix was favourable and whether epidural was available.

In the latest study, women in the induction group had a shorter overall hospital stay (owing to the lower rate of caesarean delivery). However, they spent longer in the labour and delivery unit compared with the expectant group.

Professor Hans Peter Dietz, Professor of Obstetrics and Gynaecology at Sydney Medical School is a vocal critic of the prevailing natural birth ideology. He said inducing babies at 39 weeks was a “no-brainer” if one wanted to reduce the risk of stillbirths and other perinatal complications.  He said fetal lung maturity had been demonstrated at this stage.

“The risk of stillbirth is low in Australia but it’s not zero, and there is a very small additional risk with every day that goes by. So by delivering the baby at 39 weeks, you reduce the stillbirth risk,” he said.

Professor Dietz noted the study showed no increased risk of operative vaginal delivery with induction at 39 weeks compared with expectant management, adding there might be other benefits of having a slightly smaller baby earlier, such as a lower risk of pelvic floor trauma.

A Cochrane review concluded that a policy of labour induction at or beyond term compared with expectant management was associated with fewer perinatal deaths, fewer caesarean sections and more operative vaginal births. The timing of induction in the trials reviewed ranged from 37 weeks to 41 weeks.

 *Although this finding would typically meet the standard for statistical significance (p≤0.05), in the present study it did not. This is because the authors raised the p value for statistical significance to 0.046 to compensate for having looked at the primary outcome once in the middle of the study (pre-planned interim analysis).