Stillbirth: Why is Sleeping on the Side So Important in Pregnancy?

Stillbirth: Why is Sleeping on the Side So Important in Pregnancy?

SOS - this is an acronym for both 'Sleep on side' and also 'Save our Souls'. But does sleeping on your side during pregnancy truly contribute to being able to save your precious baby's soul and reduce your risks of having a stillbirth?

Sleep is a basic aspect of life and an everyday activity that we carry out without much thought – but not if you’re pregnant. During the months your body is making another life (and several months afterwards for entirely different reasons), sleep can be yet another chore as well, especially since there is now a preferred position that doctors tell us to sleep in. Pregnant mamas have probably heard that it is best for them to sleep on their side. However, despite all that we have heard about sleeping on the side pregnancy benefits and the risks involved, this is more often easier said than done, especially for mamas who have been sleeping on their backs and tummies their whole lives prior to the pregnancy!

So is this truly something we need to pay heed to? Why is it so important to sleep on our sides during pregnancy? 


sleeping on the side pregnancy

Sleeping on the side pregnancy benefit: reduced risk of stillbirth. Photo: iStock

Sleeping on the side pregnancy 

SOS – Sleep on side: Save our souls

Sleep on side literally shortens up to SOS, which is also a popular acronym for Save Our Souls.

And indeed sleeping on your side during pregnancy might just save your baby’s soul and reduce the risk of pregnancy loss, as there have been confirmed links between stillbirth, and going to sleep in a supine position (on your back) in late pregnancy. 

According to the largest study of maternal sleep position and risk of stillbirth published in BJOG: An International Journal of Obstetrics and Gynaecology, women who suffered a stillbirth after 28 weeks gestation were 2.3 times more likely to have slept on their backs than on their sides, the night before the stillbirth occurred. 

The study took into account 291 pregnancies that ended in stillbirth and 735 women who had a live birth, and confirmed findings from earlier studies that pregnant women who go to sleep on their back after 28 weeks of pregnancy are more likely to have a stillbirth. 

In another study, published in the journal PLOS One, a supine (sleep on back) sleeping position was associated with a 3.7 times higher risk of stillbirth.

Despite not knowing for certain why the risk of stillbirth is increased in going to sleep in a supine position, researchers have several theories.

As the fetus grows, a woman lying on her back in her third trimester has the combined weight of the baby and her uterus (womb), pushing down on her and putting pressure on the main blood vessels that supply the uterus, leading to a potential restriction in blood flow/oxygen to the baby.

Other reasons could include pre-existing conditions such as sleep apnea (a condition in which breathing repeatedly starts and stops at night), and asthma, wherein in both cases she may already have trouble delivering the optimal amount of oxygen to her body and/or baby. In the event of such conditions being coupled with reduced blood flow that comes from supine sleeping, the effects could be multiplied and could result in tragedy. 

The best night-time advice for pregnant women is to sleep on their side every time they go to sleep in the third trimester, including:

  • initially going to sleep at night – the position you went to sleep in is the one held longest during the night; start off with going to sleep on your side
  • returning to sleep after any night awakenings
  • any naps taken during the day
sleeping on the side pregnancy

Pregnant women who go to sleep on their backs are at an increased risk of suffering a stillbirth. Photo: iStock

Sleeping on the side pregnancy – avoid low birth-weight in infants

Further studies have also found links between low birth weight and sleeping on your back during the third trimester.

The position you fall asleep in is often the position you stay in for the majority of the night and research suggests that lying on your back in late pregnancy can compress blood flow around your body, lowering supplies of oxygen and nutrients to the developing fetus. This may have an impact on the growth of the fetus in the womb and can result in low birth-weight in infants, leading to health problems or complications before or after they are born.

According to the main author of the study, Dr. Ngaire Anderson, “this reduction in birth weight with back sleeping could partly explain the relationship we have seen between back sleeping and elevated risk of stillbirth”.

Facing left: the right thing to do? 

Taking all this into consideration, the best sleep position during pregnancy is SOS (sleep on side) – more specifically your left side, as this position is optimum to increase the flow in the amount of blood and nutrients that reach the placenta and your baby.

Although doctors have generally recommended sleeping on your left side during pregnancy, a recent study suggests that either side is fine.


Stillbirth: Why is Sleeping on the Side So Important in Pregnancy?

SOS (Sleep on side) is the best sleep position during pregnancy. Photo: iStock


However, sleeping on the left side is still often referred to as the ideal scenario during pregnancy.

This boils down to the fact that a left-side sleeping position allows for optimal blood flow from the inferior vena cava (IVC), which is a large vein that runs parallel to your spine on the right side. This vein is responsible for carrying blood to your heart and also to your baby.

Additionally, sleeping on your left side eases the pressure off your liver and your kidneys, enabling them to function properly, which will in turn help with edema (swelling) in your hands, ankles, and feet.

It should be stated that in the result of the findings above, there was a very slight risk of compression issues with the IVC when you sleep on the right. However, if your pregnancy is going fine thus far and you are having trouble sleeping on your left side, rolling over to the right to get some sleep and avoid outcomes that could result out of sleep deprivation far outweighs the slight risk of IVC compression when lying on your right flank. 

It may be easier said than done what with sudden cramps waking you up ever so often and having to visit the bathroom to empty your bladder many times a night, but ample sleep is very essential during pregnancy. 

According to Dr. Grace Pien, an assistant professor of medicine at the Johns Hopkins University School of Medicine, “research suggests that pregnant women who are not getting enough sleep — less than 5 or 6 hours of sleep a night — probably are at increased risk for things like gestational diabetes, and potentially for things like preeclampsia.”

“I don’t think there’s clear evidence that sleeping on your right is worse than sleeping on your left,” Pien further noted. “If there’s a reason somebody is sleeping on their right because they’re more uncomfortable sleeping on their left, I don’t think there’s a reason not to do it.”

To all the pregnant mums out there, happy side-snoozing and we hope you enjoy all the sleep you can get – you’re going to need it! 


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