In the third trimester our advice is to go sleep on your side because research has shown that this is safer for baby. This includes night sleep and day time naps.
Can I sleep on my back during pregnancy?
Research has shown that in the third trimester (after 28 weeks of pregnancy) going to sleep on your back increases your risk of stillbirth. As the link has now been shown in four separate research trials, our advice is to go to sleep on your side in the third trimester because it is safer for your baby. The advice relates to any episode of sleep, including:
- going to sleep at night
- returning to sleep after any night wakenings
- day time naps.
We don’t want you to become anxious about this. If your pregnancy is uncomplicated your risk of stillbirth is low (1 in 200 babies are stillborn). Going to sleep on your side will make it even lower.
How reliable is the research?
The research linking going to sleep on your back to stillbirth is very reliable. Four case control research studies (in which information from women who have had a stillbirth is compared with information from women who have not) have been carried out into maternal sleep position and stillbirth and all have shown that there is a link.
What if I wake up on my back during the night?
The research has been focused on position going to sleep, not position during the night. If you wake up on your back, just settle back to sleep on your side.
We cannot control our position when we are asleep and a large bump is likely to be uncomfortable enough to prevent you from being on your back for long during the night. We also know that the position we go to sleep in is the position we spend the longest amount of time in during the night.
What could cause the increased risk of stillbirth?
Sleep position in the third trimester is important because if you are on your back the combined weight of baby and womb puts pressure on other organs in your body.
Researchers do not know for certain what exactly is causing the increased risk of stillbirth, but we already know the following, which could play a part :
- When sleeping/lying on your back the baby and womb put pressure on the main blood vessels that supply the uterus and this can restrict blood flow/oxygen to the baby.
- Further recent studies have shown that when a woman lies on her back in late pregnancy (compared to lying on side) the baby is less active and has changes in heart-rate patterns. This is thought to be due to lower oxygen levels in the baby when the mother lies on her back.
Does it make a difference which side I sleep on in pregnancy?
There are many websites that tell you that the left side is best to sleep on during pregnancy. This is for the following reasons:
- One of the smaller research studies, from Auckland, New Zealand, showed that women who sleep on their left side on the last night of pregnancy halved their risk of stillbirth compared to those who slept on their right. However, the same finding has not been seen in any other trial (there have been three other published research studies since then).
- Sleeping on your left has been shown to help your kidneys to get rid of waste products and fluids from your body.
Therefore, while sleeping on your left side has not conclusively been shown to reduce your risk against sleeping on your right, there are reasons that you might choose to do so.
Tips for sleeping on your side in pregnancy
- Put pillows behind you to prevent falling on your back. It won’t prevent you being on your back for certain but is likely to make it more uncomfortable.
- If you have long hair, try tying it in a low bun, which may make it uncomfortable to sleep on your back for any length of time.
- If you wake up for any reason during the night, check your position and go back to sleep on your side.
- If you are likely to nap during the day pay the same attention to sleep position during the day as you would during the night.
In the early days of pregnancy it is fine to sleep on your stomach. Your bump will not start showing until the second trimester and sleeping on your stomach is unlikely to be uncomfortable. In the third trimester, you will have a large bump and it is very unlikely that you would choose this position. However, if you do wake up on your stomach, don’t worry, just roll onto your side.
Heazell AEP, Li M, Budd J, Thompson JMD, Stacey T, Cronin RS, Martin B, Roberts D, Mitchell EA, McCowan LME. Association between maternal sleep practices and late stillbirth – findings from a stillbirth case-control study. BJOG2017; https://doi.org/10.1111/1471-0528.14967.
Stacey T1, Thompson JM, Mitchell EA, Ekeroma AJ, Zuccollo JM, McCowan LM.
Association between maternal sleep practices and risk of late stillbirth: a case-control study. BMJ. 2011 Jun 14;342:d3403. doi: 10.1136/bmj.d3403.
Gordon A1, Raynes-Greenow C, Bond D, Morris J, Rawlinson W, Jeffery H. Sleep position, fetal growth restriction, and late-pregnancy stillbirth: the Sydney stillbirth study. Obstet Gynecol. 2015 Feb;125(2):347-55. doi: 10.1097/AOG.0000000000000627.
Lesley ME, McCowan LME, Thompson JMD, Cronin RS 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 https://doi.org/10.1371/journal.pone.0179396
Jeffreys RM, Stepanchak W, Lopez B, Hardis J, Clapp JF, 3rd. Uterine blood flow during supine rest and exercise after 28 weeks of gestation. BJOG : an international journal of obstetrics and gynaecology. 2006 Nov;113(11):1239-47
Khatib N, Weiner Z, Beloosesky R, Vitner D, Thaler I. The effect of maternal supine position on umbilical and cerebral blood flow indices. European journal of obstetrics, gynecology, and reproductive biology. 2014 Apr;175:112-4.
Stone PR, Burgess W, McIntyre JP, Gunn AJ, Lear CA, Bennet L, et al. Effect of maternal position on fetal behavioural state and heart rate variability in healthy late gestation pregnancy. The Journal of Physiology. 2017 Feb 15;595(4):1213-21.
Murray I, Hassall J. 2014. Change and adaptation in pregnancy. In: Marshall J, Raynor M. eds. Myles Textbook for Midwives. 16th ed. Edinburgh: Churchill Livingstone, 143-177Hide details
New research has found links between low birth weight and sleeping on your back during the third trimester.
A3 poster about two of the most important things for women to remember in the third trimester, monitoring fetal movements and going to sleep on your side.
We have received a huge amount of coverage for our #SleepOnSide campaign this week. These are some of the commonly asked questions about the research and the campaign, and our responses.
Nicola writes beautiful and uplifting posts about her experience of losing her first baby, Winter Wolfe, and parenting her second child, Raven Rain. Here she explains why she’s supporting Tommy’s Sleep On Side campaign.
We showed the Sleep on Side campaign and research to some well-known mums and filmed their reactions.
Press release for the launch of the Midlands and North of England Stillbirth Study (MiNESS) research and the Sleep On Side campaign
A filmed presentation about the four research studies into maternal sleep position and pregnancy that led to the Sleep On Side campaign. Featuring Professor Alex Heazell.
This film has been developed with women and clinicians as part of the Sleep On Side campaign to raise awareness of this important message.
We are raising awareness of the link between the mother sleeping on her back in the third trimester and stillbirth.
ℹLast reviewed on November 20th, 2017. Next review date November 20th, 2020.
By Sheila robb (not verified) on 16 Jun 2017 - 08:51
There are other reasons not just this.
By Midwife @Tommys on 16 Jun 2017 - 16:03
Hi, absolutely there are other reasons however this is new research and evidence coming out which we try to let all women know about which can help to lower risk of stillbirth.