The study of nearly 80,000 UK women, published in the journal PLOS Medicine, showed that inducing these women one to two weeks earlier was linked to the risk of baby death falling from 26 per 10,000 pregnancies to eight per 10,000 pregnancies.
“The number of first-time mothers over the age of 35 is rising,” said Hannah Knight, lead author from the London School of Hygiene & Tropical Medicine.
“This study represents the strongest evidence yet that moving the offer of induction forward to 40 weeks might reduce the risk of stillbirth in this specific age group, which we know face a greater risk of stillbirth and neonatal death.”
Current UK national guidelines recommend induction of labour to be offered to pregnant women at between 41 and 42 weeks of gestation (one to two weeks after their due date).
In the study, the authors used data from English Hospital Episode Statistics covering 77,327 first-time mothers aged 35-50, to determine whether an earlier induction was associated with a change in risk to mother or child.
They compared women who were induced at 39, 40 and 41 weeks of gestation. They found that pregnant women who were induced at 40 weeks had a “lower risk of perinatal death of two thirds” compared to women who received care according to current guidelines.
Knight added: “Whilst our study suggests bringing forward the routine offer of induction of labour to 40 weeks of gestation in first-time mums aged 35 or over may reduce the risk of perinatal death, there are other important factors to consider.
“There are potential downsides to such a policy, such as acceptability of induction of labour to women and the increased demand on resources.
“Further studies are needed to examine the impact of such a change in policy on NHS costs and women’s satisfaction.”
Senior author Professor Gordon Smith, head of the department of obstetrics and gynaecology at the University of Cambridge, believes women over the age of 35 should consider inducing labour at their due date.
“Our best estimate is that one stillbirth would be prevented for every 562 inductions of labour,” he said.
“Some women might prefer to avoid induction and to accept this small risk. Other women may opt for induction given concerns about the possibility of stillbirth.
“But a key aspect of the paper is that this analysis provides the best evidence for the magnitude of the risk and allows women to make an informed choice.”
Our best estimate is that one stillbirth would be prevented for every 562 inductions of labour." Senior author Professor Gordon Smith, head of the department of obstetrics and gynaecology, University of Cambridge
Professor Lesley Regan, president of the Royal College of Obstetricians and Gynaecologists (RCOG), said the implications of such a change in policy - inducing all women aged 35 and over on their due date - would be “enormous” for both the health service and women themselves.
“Further research to determine the impact of such a change in practice is needed,” she explained.
“While induction is safe and studies have shown no short-term adverse impact on mother or baby, induction of labour represents an intervention, is associated with costs to the service, and can be a more prolonged process than spontaneous labour.
“These findings should help women over the age of 35 make an informed choice with regards to induction of labour and are likely to influence the production of future guidelines.
“Through our Each Baby Counts initiative and in partnership with the NHS and Department of Health, the RCOG is committed to halving the number of babies who are stillborn, suffer a neonatal death or severe brain injury by 2030.”