Inducing birth for women whose pregnancy lasts to 41 weeks could reduce the death toll from stillbirths, say experts, following publication of the results of an important trial in which six babies died after spending longer in the womb.

The results of the trial in Sweden, revealed last month in the Guardian, may change practice around the world. They confirm what experience and smaller studies have suggested – that there is a small increased risk of stillbirth for babies after 41 weeks’ gestation. The trial was stopped early after five babies of women who were more than 41 weeks’ pregnant were stillborn and one died shortly after birth.

Dr Sarah Stock, honorary consultant in maternal and foetal medicine at the University of Edinburgh, said it would now be hard not to offer induction to every woman at 41 weeks. “This study adds to the growing body of evidence that induction of labour, at or beyond term gestation, is safer for babies, without increasing caesarean section or other complications for mothers,” she said.

“This carefully conducted Swedish study suggests that offering pregnant women induction of labour at 41 weeks’ gestation, rather than waiting until 42 weeks’ gestation, could reduce baby deaths.”

The normal term for pregnancy is considered to be 40 weeks, but some babies arrive earlier and some later. In the UK, guidelines recommend that women be offered the option of induction – usually a pessary to “ripen” the cervix and start labour – if the pregnancy continues beyond 41 weeks. The current practice is to induce by 42 weeks, but, the authors of the study say, several smaller studies have suggested the risks to the baby of death or harm have already increased significantly by 41 weeks.

“The risk of stillbirth increases gradually from 39 weeks of gestation and increases exponentially as the pregnancy approaches 42 weeks,” write assistant professor Ulla-Britt Wennerholm from Gothenburg University and colleagues in the British Medical Journal.

The trial was set up specifically to try to answer the question of the safety of allowing pregnancies to continue beyond 41 weeks. It enrolled 2,760 women with an average age of 31 who had a singleton, uncomplicated pregnancy in one of 14 Swedish hospitals between 2016 and 2018. Half were randomly assigned to induction at 41 weeks and the rest to “expectant management” until 42 weeks.

The general health of the babies and mothers was no different between the two groups, although babies induced at 41 weeks were less likely to end up in specialist neonatal care or have complications such as jaundice. But six babies died after 41 weeks. Inducing birth at 41 weeks could prevent one death in 230 late pregnancies, the authors estimate.

Stock said some women had ultrasound checks between 41 and 42 weeks to check on the health of their babies, “but the study was not large enough to see if this ‘watchful waiting’ approach was any safer. It now seems hard to justify denying women the option of induction of labour when they reach 41 weeks’ gestation. Maternity services must be adequately resourced and staffed to offer increasing numbers of induction of labour safely, in a setting that works for women.”

Prof Alexander Heazell, spokesperson for the Royal College of Obstetricians and Gynaecologists and clinical director of Tommy’s Research Centre on Stillbirth, said pregnancies that reach or pass 41 weeks are usually safe and straightforward but there was a small increased risk of stillbirth.

“We are saddened by reports of babies who died during a research trial in Sweden. The loss of a baby is a devastating tragedy for parents, to the wider family, and the healthcare professionals involved,” he said.

“Current UK guidance recommends that induction of labour should be offered to women with uncomplicated pregnancies who go beyond 41 weeks to avoid the risks of prolonged pregnancy, including stillbirth. We support the continual review of clinical guidelines as new evidence emerges to ensure best practice.

“A woman’s individual needs and preferences should always be taken into account and they must have the opportunity to make informed decisions in partnership with their healthcare professionals.”

Elizabeth Duff, senior policy adviser at the National Childbirth Trust, said: “This research is welcome and adds to our knowledge about pregnancies that continue beyond 40 weeks. However, there’s no one-size-fits-all approach to childbirth. Women should be provided with information about the benefits and risks of induction and their decisions respected.

“We have heard of women having the procedure delayed due to their maternity unit’s lack of capacity. This is unacceptable as it leaves pregnant women anxious about the risk of stillbirth.”