Sleep position and still birth risk

August 27, 2019

New research confirms that the risk of stillbirth is doubled if women go to sleep on their backs in the third trimester. In the UK around 1 in 225 pregnancies end in stillbirth. The largest study to examine maternal sleep and late stillbirth is the Midlands and North of England Stillbirth study which found that women that go to sleep on their back in the third trimester have a 2.3 fold increase in stillbirth, compared with women that go to sleep on their side. This means that if all pregnant women went to sleep on their side in the third trimester there could be a 3.7% decrease in stillbirth, saving 130 babies a year. Similar findings were also found in earlier studies in New Zealand and Australia.

Although it is difficult for research to tell exactly why sleeping on the back increases the risk of stillbirth, there are several theories. When women lay on their back in the third trimester it is possible that the combined weight of the baby and the uterus puts pressure on the main blood vessels that supply that uterus, which can restrict blood flow/oxygen to the baby. Another possible explanation is that breathing is disturbed during sleep, which is made worse when a woman sleeps on her back, particularly in overweight in obese women, which also increase the risk of stillbirth.

Current advice to pregnant women is to sleep on their side for any episode of sleeping including, going to sleep at night, returning to sleep after night wakening and also during day time naps. However, it is important to note that since the going to sleep position is the one held longest during the night, women should not be alarmed if they wake up on their backs, but simply roll back into their side. There was no difference found in the risk of going to sleep on the left or right side.

Tips for going to sleep on the side in the third trimester include putting a pillow or pillows behind the back to encourage side sleeping and checking sleeping position during night wakening and if needed, adjusting the position to being on the side.



  1. A, Heazell. J, Budd., J, Thompson. T, Stacey., R, Cronin. B, Martin. D, Roberts. E, Mitchen, L, McCowan. (2017). Association between maternal sleep practices and late stillbirth– findings from a stillbirth case-control study. British Journal of Obstetrics and Gynaecology
  2. M, Lesley. L, McCowan. J, Thompson., R, Cronin et al. (2017). Going to sleep in the supine position is a modifiable risk factor for late pregnancy stillbirth; Findings from the New Zealand multicentre stillbirth case-control study. PLOS One.


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