Safest sleep position in pregnancy

In the third trimester of pregnancy going to sleep on your side has been shown to help prevent late stillbirth

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 three 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.

Stillbirth is not common, affecting 1 in 200 babies. Even with this increased risk, it is important to note that someone with an uncomplicated pregnancy is still at low risk of having a stillbirth. There are also other modifiable (things you can change) factors that put you at higher risk, smoking for example.

How reliable is the research?

The research linking going to sleep on your back to stillbirth is very reliable. Three research trials have been carried out investigating the topic and all have shown that there is a link. A further trial, led by Professor Alex Heazell, Clinical Director of the Tommy's research centre in Manchester University, is due to report in a couple of months.

What if I wake up on my back in pregnancy?

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.

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 two 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, there are reasons that you might choose to do so.

Can I fall asleep in an armchair in the third trimester?

As the advice is to go to sleep on your side in the third trimester, it may be best to avoid falling asleep in a chair or sofa that doesn’t allow this position. One of the research studies that showed sleeping on your side is best also showed that having a daytime nap every day is also associated with an increased risk of stillbirth. Researchers do not know the reason for this but it may be linked to the slumped position you may end up in and its affect on blood flow. If you do take a nap in the daytime, the advice is to lie on your side.

How can I be safe on a sun-lounger in the third trimester?

As a general rule, avoid positions in which your bump is pressing down on you. If you are planning a sun holiday in your third trimester (or if the sun shines at home) keep your sun-lounger in an upright position while you are awake. If you think you might like to sleep in the sun (or shade!), put the lounger in a flat position and go to sleep on your side. Be wary of ending up on your back in sun loungers that do not allow these positions.

Is it safe to exercise on my back?

No, it is best to avoid being on your back in the third trimester. Women who practise yoga or other forms of exercise in which you may end up on your back have long been advised not to spend time on your back, and to avoid positions in which you need to be on your back.

Tips for sleeping on your side in pregnancy

  • It might help to start the night on a different side to that you wish to end up sleeping in, and then settle eventually to the left side, as changing position before falling asleep is common.
  • 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 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.

Can I sleep on my stomach in pregnancy?

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 second trimester, there is no research to show that sleeping on your stomach is harmful but you may find that it is getting more uncomfortable and you are choosing different positions just to get a better night’s sleep. 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.

Sources

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.

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.

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, 143-177

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Comments

  • By Anonymous (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.

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