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Inducing labour in late pregnancies is safer approach

Study halted early after six deaths occurred

Adrian O'Dowd

Thursday, 21 November 2019

Pregnant women who have their labour induced at 41 weeks could have a lower risk of newborn deaths compared with expectant management (a “wait and see” approach) until 42 weeks, suggests a study* published today by The BMJ.

Researchers have recommended that although the overall risk of death at 42 weeks was low, induction of labour should be offered to women no later than 41 full weeks because doing so was associated with a lower risk of newborn death.

It is generally accepted that there is an increased risk of adverse perinatal outcomes for both mother and baby at or beyond 42 weeks of pregnancy.

Some previous studies have suggested that inducing labour from 41 weeks onwards improves these outcomes, but there is no international consensus on how to manage healthy pregnancies lasting more than 41 weeks.

Current practice in the UK and Scandinavia is to induce delivery for all women who have not gone into labour by 42 weeks.

Researchers led by Sahlgrenska University Hospital in Gothenburg, Sweden, set out to compare induction of labour at 41 weeks with expectant management until 42 weeks in low risk pregnancies.

Their trial involved 2,760 women (average age 31) with an uncomplicated, single pregnancy recruited from 14 Swedish hospitals between 2016 and 2018.

Women were randomly assigned to induction of labour at 41 weeks (1,381) or expectant management (1,379) until induction at 42 weeks if necessary.

The main outcome was a combined measure of babies’ health, including stillbirth or death in the first few days of life, Apgar score less than seven at five minutes, low oxygen levels, and breathing problems.

Other outcomes included admission to an intensive care baby unit, Apgar score less than four at five minutes, birth weight, pneumonia, or sepsis.

Results showed that for the main outcome measure, there was no significant difference between the groups – 2.4% of women in the induction group had an adverse perinatal outcome compared with 2.2% in the expectant management group.

Other outcomes, such as caesarean sections and mothers’ health after giving birth, also did not differ between the groups.

However, six babies in the expectant management group died compared with none in the induction group, and the trial was stopped early.

The researchers estimated that, for every 230 women induced at 41 weeks, one perinatal death would be prevented.

Their study had some limitations, they acknowledged, such as differences in hospital policies and practices, that could have affected the results.

Nevertheless, they said: “Women with low risk pregnancies should be informed of the risk profile of induction of labour versus expectant management and offered induction of labour no later than at 41 full weeks. This could be one (of few) interventions that reduces stillbirth.”

The view was supported in a linked editorial** by Professor Sara Kenyon and colleagues from the Institute of Applied Research Centre at the University of Birmingham, who said: “41 weeks looks like the safer option for women and their babies.

“Choice is important within maternity care, and clear information about available options should be accessible to all pregnant women, enabling them to make fully informed and timely decisions.”

*Wennerholm U-B, et al. Induction of labour at 41 weeks versus expectant management until 42 weeks (Swedish post-term induction study, SWEPIS): multicentre, open label, randomised superiority trial. BMJ 2019;367:l6131. DOI:10.1136/bmj.l6131

**Kenyon S, Middleton L, Skrybant M, et al. Editorial: When to induce late term pregnancies. BMJ 2019;367:l6486. DOI:10.1136/bmj.l6486

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