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Inducing birth at 41 weeks 'may reduce risk of stillbirth'

"Induction recommended for women still pregnant at 41 weeks," reports The Guardian.

Most women give birth when they are around 37 to 40 weeks pregnant. After this time, the chance of problems begins to rise. If a woman in the UK has not given birth after 41 weeks of pregnancy, most will be offered an induction of their labour. This means they will have procedures to start their labour.

Most international guidelines recommend inducing labour somewhere between 41 and 42 weeks of pregnancy, but there has been no clear agreement on specifically when. There has also been no clear evidence from clinical trials to show which approach is better.

A study in Sweden set out to compare which approach was better in 2,760 mothers and their babies. They were looking for any 1 of several adverse outcomes for newborns, including serious health complications, need for help breathing (ventilation) and stillbirth.

Researchers assigned the women to 1 of 2 groups; those who would be induced, and those offered "expectant management" (meaning a woman was offered an induction at 42 weeks if she had not gone into labour naturally in the meantime). The researchers found that the combined outcomes affected 2.4% of induced births and 2.2% of those with expectant management.

However, the study was stopped early because 5 stillbirths occurred in the expectant management group. No still births occurred in the group who received induction at 41 weeks. The researchers decided it would be unethical to continue the trial because of this.

In general, the trial supports understanding that there is increased risk of complications when a pregnancy continues beyond 40 weeks (full term). They suggest it is worth considering induction at 41 weeks.

Thankfully, death of a baby around the time of birth is rare in the UK. Find out more about pregnancy and birth.

Where did the story come from?

The researchers who carried out the study were from Gothenburg University, Karolinska University Hospital, Danderyd Hospital, Örebro University and Uppsala University, all in Sweden. The study was funded by the Swedish government and published in the peer reviewed British Medical Journal on an open-access basis, meaning it is free to read online.

The Guardian, The Times and The Sun all covered the story accurately, making it clear that women should be offered induction after 41 weeks on the NHS. However, Mail Online reported that the study "goes against NHS practice, which says doctors should offer to induce labour at the 42nd week if a woman makes it that far without giving birth." Guidelines from the UK's National Institute for Health and Clinical Excellent (NICE) clearly state: "women with uncomplicated pregnancies should be offered induction of labour beyond 41 weeks."

What kind of research was this?

This was a randomised controlled trial (RCT). This is usually the best way to compare two types of treatment, to see which works best, because the randomisation process should balance out any differences in characteristics between groups.

When a trial is showing clear evidence at an early stage that one course of action is preferable, particularly when there are serious potential harms, as in this trial, it is usual to end a trial early as it would be unethical to continue.

What did the research involve?

The study was carried out at 14 hospitals in Sweden between 2016 and 2018. Researchers recruited women with a single (1 baby), uncomplicated pregnancy who were 41 weeks pregnant. They were told about the study when they were 40 weeks pregnant.

Women were randomly assigned to 1 of 2 groups:

  1. The induction group, where their labour was induced within 24 hours (if they did not go into labour spontaneously in that time).
  2. The expectant management group, where they waited to see if labour started spontaneously, but the mothers were induced at 42 weeks if labour had not started by then.

They were looking to see if the babies had any combination of a wide range of outcomes (a composite outcome), including:

  • stillbirth and death
  • a low Apgar score (a test of a baby's health at birth)
  • bleeding in the brain
  • the need for breathing support
  • signs that the baby had breathed in some of its first poo (meconium)

They planned to recruit 10,038 pregnant women. Recruitment started in May 2016 but was halted in October 2018 when 2,762 women had been recruited.

Women were not included in the trial if they had a previous caesarean section or other uterine surgery, or health problems including diabetes, high blood pressure, or if their baby showed signs of abnormal development or was smaller than it should be.

What were the basic results?

The trial was stopped because there were 5 stillbirths in the expectant management group of 1,379 pregnancies and 1 baby died soon after birth. That meant 0.4% of the babies died in the expectant management group, which was statistically significant. There were no stillbirths or early neonatal deaths in the group of 1,381 pregnancies that were induced at 41 weeks.

The data showed no difference in the combined outcomes between groups, only in the individual complication of stillbirths and death. 2.4% of babies in the induction group and 2.2% of babies in the expectant management group had one or more of the serious newborn complication (including stillbirth and death). Among all the complications, a low Apgar score was most common, affecting 1.3% of the induction group and 1.2% of the expectant management group.

The researchers calculated that 230 pregnant women would need to have labour induced at 41 weeks to prevent 1 stillbirth.

How did the researchers interpret the results?

The researchers said: "Although these results should be interpreted cautiously, induction of labour ought to be offered to women no later than at 41 weeks and could be 1 (of a few) things that could be done to reduce the rate of stillbirths."

Conclusion

Fortunately the death of a baby is rare in the UK, but every death is a tragedy that causes huge heartbreak to a family. Similarly, serious newborn illness and the need for intensive care as a result of complications causes distress and can sometimes have a long-term impact for both the child and their family. Pregnant women reading this story may be worried by the headlines warning of the risks if a pregnancy goes beyond 41 weeks.

However, the study backs up current guidance to the NHS, which is that women who reach 41 weeks of pregnancy should be offered induction. This does not mean they have to accept the procedure. But, the results of the study confirm that women should be given the option of induction, and clear information about the benefits and risks.

It's not possible to draw certain conclusions from the study, because it was stopped early without recruiting the numbers of women it had intended to. Also, because many complications, such as stillbirths, are rare, it would be difficult to study enough women in order to obtain results that would provide reliable statistical evidence for every complication. That's why the researchers chose a combination of events as their main outcome. However, this may be some of the strongest evidence we can get. It would not be ethical to put the health of mothers and their babies at risk for the sake of research when the results for newborn deaths seem clear.

The researchers also point out that all cases of stillbirth and death happened in pregnancies where the woman had not given birth before. They suggest that this group of first-time mothers might need to be given "particular attention" if they reach 41 weeks of pregnancy.

Find out more about what happens when a pregnancy goes to 41 weeks.

Analysis by Bazian
Edited by NHS Website