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Stillbirth risk is doubled if pregnant women sleep on their backs in third trimester

News 20 November 2017

New research published today in BJOG: An International Journal of Obstetrics and Gynaecology suggests that the risk of stillbirth is doubled if pregnant women sleep on their backs during the third trimester. 

The Midlands and North of England Stillbirth Study (MiNESS) is the largest study of maternal sleep position and risk of stillbirth. It looked at 291 pregnancies that ended in stillbirth and 735 women who had a live birth.  

The findings suggest women who go to sleep on their back  - known as the supine position - have a 2.3 fold increase in risk of late stillbirth (after 28 weeks of gestation) compared with women who sleep on their side. It also estimates that if all pregnant women in the UK went to sleep on their side in the third trimester, there would be a 3.7% decrease in stillbirth – equivalent saving around 130 babies’ lives a year.

Led by the charity Tommy’s, a public health campaign called ‘Sleep on Side’ launches today and aims to educate women about the risk of going to sleep on their back in late pregnancy.

The advice to pregnant women is to go to sleep on their side for any episode of sleep in the third trimester, including:

  • going to sleep at night
  • returning to sleep after any night wakenings
  • day time naps

As the going-to-sleep position is the one held longest during the night, women should not be concerned if they wake up on their back, but should simply roll back onto their side.

The MiNESS study did not find a difference in risk between sleeping on the right or left side. A previous study did show that sleeping on the right increased the risk, but as this was not found in the other three studies, the Tommy’s Sleep On Side campaign recommends that women can go to sleep on either side.

Although the research did not determine the cause for the increased risk, one possibility is that the combined weight of the baby and uterus in the third trimester places pressure on the main blood vessels that supply the uterus, restricting oxygen flow to the baby. Other possible explanations include disturbed breathing during sleep, which is more likely when sleeping on the back.

Lead author of the study, Professor Alex Heazell, Clinical Director at the Tommy’s Stillbirth Research Centre at St Mary’s Hospital, Manchester, said:

“Around 11 babies are stillborn every day in the UK. Stillbirth is devastating, with long-lasting effects on bereaved parents. Parents want to know why their baby has died, whether it might happen again if they try for another baby and what they can do to avoid further stillbirth.”

“We believe that identifying, and avoiding, risk factors that are strongly associated with stillbirth will reduce the number of babies who are stillborn. The MiNESS results have implications as they indicate that if women go to sleep on their side in late pregnancy rather than on their back there could be 3.7% reduction in stillbirth.”

Mr Edward Morris, Vice President for Clinical Quality and spokesperson for the Royal College of Obstetricians and Gynaecologists, said: 

“This is an important study which adds to the growing body of evidence that sleep position in late pregnancy is a modifiable risk factor for stillbirth. This new research is extremely welcome as a significant number of stillbirths remain unexplained, particularly those in late pregnancy. The impact of stillbirth on parents and professionals is devastating and the RCOG is committed to working collaboratively on research, audit and training for healthcare professionals in order to achieve a substantial reduction in the UK stillbirth rate.


Note to Editors

This article will be included in the BJOG special issue on Stillbirth, due to publish January 2018. A video abstract and plain language summary is available. 

For media enquiries please contact the RCOG press office on +44 (0)20 7045 6773 or email

Association between maternal sleep practices and late stillbirth – findings from a stillbirth case-control study. BJOG. Heazell, A. et al

About BJOG
BJOG: An International Journal of Obstetrics and Gynaecology is owned by the Royal College of Obstetricians and Gynaecologists (RCOG) but is editorially independent and published monthly by Wiley. The journal features original, peer-reviewed, high-quality medical research in all areas of obstetrics and gynaecology worldwide. Please quote ‘BJOG’ or ‘BJOG: An International Journal of Obstetrics and Gynaecology’ when referring to the journal. To keep up to date with our latest papers, follow @BJOGTweets.

About the RCOG

The Royal College of Obstetricians and Gynaecologists is a medical charity that champions the provision of high quality women’s healthcare in the UK and beyond. It is dedicated to encouraging the study and advancing the science and practice of obstetrics and gynaecology. It does this through postgraduate medical education and training and the publication of clinical guidelines and reports on aspects of the specialty and service provision.