Risk of stillbirth 'doubles when pregnant women sleep on back'

The risk of stillbirth is doubled if women go to sleep on their backs in the third trimester, new research claims.

If all pregnant women slept on their sides from week 27 onward, there would be a 3.7% decrease in stillbirth, saving around 130 babies’ lives a year, The Midlands and North of England Stillbirth Study (MiNESS) found.

Internationally, this advice has the potential to save up to 100,000 babies a year.

It comes as the Sleep On Side campaign, led by the charity Tommy’s, launched to educate women about the risk of going to sleep on their back in late pregnancy.

Around 1 in 225 pregnancies in the UK end in stillbirth.

MiNESS found that women who go to sleep on their backs have a 2.3-fold increased risk of late stillbirth, after 28 weeks’ gestation, compared with women who go to sleep on their side.

It is unclear why the risk is increased but researchers have suggested several theories.

In the third trimester, when the woman is lying on her back, the combined weight of baby and uterus (womb) puts pressure on the main blood vessels that supply the uterus and this can restrict blood flow and oxygen to the baby.

Other possible explanations include disturbed breathing during sleep, which is worse when a woman sleeps on her back and in overweight or obese women, who also have an increased risk of stillbirth.

Led by Professor Alexander Heazell, Clinical Director at the Tommy’s Stillbirth Research Centre at St Mary’s Hospital, Manchester, MiNESS is the largest study to examine maternal sleep and late stillbirth.

It looked into 291 pregnancies that ended in stillbirth and 735 women who had a live birth. It confirms findings from earlier studies in New Zealand and Australia that, in the third trimester, pregnant women who go to sleep on their back are more likely to have a stillbirth.

For advice on the best sleep positions to use in pregnancy, see the Tommy's website here.