The risk of stillbirth is doubled if women go to sleep on their backs in the third trimester, new research has confirmed.
The Midlands and North of England Stillbirth Study (MiNESS) was published today in BJOG.
It found that women who go to sleep in the supine position have a 2.3-fold increased risk of late stillbirth, after 28 weeks’ gestation, compared with women who go to sleep on their side.
If all pregnant women in the UK went to sleep on their side in the third trimester, MiNESS estimates a 3.7% decrease in stillbirth, saving around 130 babies’ lives a year.
Internationally, this advice has the potential to save up to 100,000 babies a year.
The increased risk associated with women going to sleep on their back has now been demonstrated consistently by four studies in women of different ethnicities and in different countries.
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.
Although researchers cannot say for certain why the risk is increased, there are 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/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.
The advice to pregnant women is to go to sleep on their side for sleep and naps in the third trimester.
As the going-to-sleep position is the one held longest during the night, women should be unconcerned if they wake up on their back, but should simply roll back onto their side.
RCM director for midwifery Louise Silverton said: ‘This addition to current knowledge is very welcome. The Tommy’s campaign and the research findings are a great example of how through making small changes we can begin to bring down stillbirth rates. It is a simple change that can make a difference and it will be important to ensure that this is communicated effectively to women,’ she said.
The research has been funded by four charities: Action Medical Research, Curekids, Sands and Tommy’s.
Tommy’s is leading the #SleepOnSide campaign (tommys.org/sleeponside), which is endorsed by NHS England, the RCOG, the RCM and the Royal College of GPs.
The Sleep On Side campaign animation can be viewed below: