Why Sleeping on Your Side is Crucial During Pregnancy

Sleep, a topic that gets spoken of with frustration and angst. We all know you need a good night's sleep more than ever, it's unfortunately harder than ever to get. Finding a comfortable sleep position can be challenging with your growing bump, and not every position works during pregnancy.

Here’s what you need to know to stay comfortable and safe.

Sleeping on your side is the best position for you and your baby during pregnancy, especially once you're more than halfway (28 weeks) through your pregnancy.

Sleeping on your side places the least pressure on your veins and internal organs. This ensures the best blood flow to your uterus, which means your baby will get maximum nutrients and oxygen. Good circulation also helps you by reducing potential swelling, varicose veins in your legs, and hemorrhoids (arghh!).

Why is sleeping on your side recommended?

Each year, in New Zealand, approximately 160 babies are stillborn in the last three months of pregnancy. It’s estimated that if all pregnant women go to sleep on their side from 28 weeks of pregnancy, compared with going to sleep on your back, there could be a 10 percent decrease in late stillbirth nationally. When a healthy mother lies on her back (supine position) in late pregnancy the uterus compresses the main abdominal vein [inferior vena cava (IVC)] reducing the IVC blood flow by more than 80%. The aorta is also partially compressed by the pregnant uterus with an approximate 30% reduction in flow - that's a significant reduction! And, sleeping on your left has been shown to help your kidneys to get rid of waste products and fluids from your body - bonus!

‘Sleep on Side; Stillbirth Prevention Campaign’ is a public health messaging campaign by the University of Auckland, Cure Kids and the Ministry of Health, that is designed to provide pregnant people with vital information that may reduce the risk of stillbirth in the late stages of pregnancy.

Cure Kids has supported the programme of research, which has provided the evidence for the ‘Sleep on Side; Stillbirth Prevention Campaign’ since 2007, enabling New Zealand researchers to lead the way with these internationally significant findings.

Professor Lesley McCowan, Head of The University of Auckland’s Department of Obstetrics and Gynaecology, and her team of New Zealand researchers have been at the forefront of international research looking at risk factors for stillbirth for nearly 10 years. The conclusion from four studies – two by Professor McCowan in New Zealand, one in Australia and one from the UK – which analysed more than 800 late pregnancy stillbirth cases, reveals a 2.5 to 6 - fold increase in the risk of late stillbirth if women go to sleep lying on their back.

I'm not a side sleeper. How can I make the switch to sleeping on my side?

If you are used to sleeping on your back or tummy, you might try to make the transition to your left side early in your pregnancy.

• Use pillows under your belly, between your legs, and behind your back.

• Lie in a half-sitting position, propped up against some pillows, which can be helpful if you suffer from heartburn too.

• 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 nap during the day pay the same attention to your sleep position during the day as you would during the night.

Is sleeping on your back that risky?

If you typically sleep on your back (supine), it's safe to continue doing so through the first trimester. But as your uterus gets heavier around 28 weeks, it's best to sleep on your left side.

That's because lying on your back allows your growing uterus to compress the IVC (mentioned above), which could theoretically interfere with the flow of blood and nutrients to your placenta and baby. It can also result in decreased blood flow for you, which may cause dizziness, shortness of breath, or a fast heart rate. Back sleeping can also contribute to the circulation problems mentioned above (varicose veins, hemorrhoids, swelling) as well as muscle aches, pains and snoring, which can lead to sleep apnea.

Don't be alarmed if you go to sleep on your side and wake up on your back. Just shift your position back to your left side and go back to sleep. The important thing is to start every sleep (daytime naps and going to sleep at night) lying on your left side and settle back to sleep on your side when you wake up.

Sleep is the time when your body re-sets and repairs itself. It’s when your brain makes memories, making it an ally in your battle against baby brain. It’s how your blood vessels restore themselves, which is especially important now that they’re under increased pressure from the extra blood flow required to support your baby.

Sleep also keeps your immune system — which is suppressed to support your pregnancy — healthy. And sleep controls how your body reacts to insulin; not getting enough results in a higher blood sugar level, upping your risk of gestational diabetes.