Safest Sleeping Position in Pregnancy: Side Sleeping From 28 Weeks

What is the safest sleeping position during pregnancy?

The safest position to go to sleep in during pregnancy is on your side, either left or right, according to the NHS, which says research suggests that after 28 weeks, falling asleep on your back can double the risk of stillbirth. ACOG (the American College of Obstetricians and Gynecologists) says sleeping on your side during the second and third trimesters may be best.

The 28-week threshold comes from the NHS in the UK. ACOG gives its advice by trimester and names no week.

The advice is about the position you go to sleep in. The NHS applies it to going to sleep at night, getting back to sleep after waking in the night, and daytime naps. The authors of a 2019 meta-analysis on sleep position point out that the position you first go to sleep in is the one you stay in longest overnight, so it may have the greatest effect on the baby.

Why should you not sleep on your back after 28 weeks?

Research suggests that going to sleep on your back after 28 weeks can increase the risk of stillbirth, the NHS says, and it is thought this may be to do with the flow of blood and oxygen to the baby. ACOG explains that in the second and third trimesters, lying on your back may compress a major blood vessel that takes blood to the uterus, which can make you feel dizzy and may reduce blood flow to the fetus.

A 2019 meta-analysis in the journal eClinicalMedicine combined individual data from five case-control studies: 851 late stillbirths and 2,257 comparison pregnancies. Going to sleep on the back was linked to 2.6 times the odds of stillbirth at 28 weeks or later, compared with going to sleep on the left side. The authors estimated that late stillbirths could fall by 5.8% if everyone 28 weeks or more pregnant settled to sleep on their side.

The same paper gives late stillbirth rates of 1.3 to 8.8 per 1,000 births across high-income countries. Its authors note that many stillbirth risk factors cannot be changed during pregnancy, and the position you go to sleep in is one that can.

Is it safe to sleep on your back before 28 weeks?

Sleeping on your back before 28 weeks does not appear to raise the risk of complications, according to a large NIH-funded study. In that study of more than 8,700 women, reported by NICHD in 2019, sleeping on the back or side through the 30th week of pregnancy did not appear to increase the risk of stillbirth, reduced size at birth or high blood pressure disorders. Among more than 400 women who slept with a device that recorded their position, those who slept on their back more than half the time were no more likely to have a complication.

The researchers cautioned that they looked at sleep position only up to 30 weeks, so the study says nothing about back or right-side sleeping late in pregnancy. The NHS advice to go to sleep on your side starts at 28 weeks. ACOG gives another reason to turn over as your belly grows: sleeping on your back puts the weight of the uterus on your spine and back muscles. Back pain in pregnancy has its own article.

Is it better to sleep on your left or right side?

Going to sleep on your left or right side appears equally safe, according to the 2019 meta-analysis, which found similar odds of late stillbirth for the two sides. The NHS says the safest position is on your side, either left or right, and the NICHD-funded study found no extra risk from right-side sleeping through week 30.

Dr. Anne Srisuro, an ob-gyn writing an Expert View piece on ACOG's website, says that sleeping on your left side through the whole pregnancy is "difficult and not necessary", and that you can sleep on either side.

What should you do if you wake up on your back?

If you wake up on your back, turn onto your side and go back to sleep. The NHS says not to worry if this happens, and Dr. Srisuro says not to panic and just turn to one side or the other.

For side sleeping, ACOG suggests keeping one or both knees bent. A pillow between your knees and another under your belly may help, or you can try a full-length body pillow. The NHS suggests supporting your bump with pillows and putting a pillow between your knees.

As the bump grows, the NHS says lying down can become uncomfortable and you may need to pee a lot. It suggests avoiding tea, coffee and cola in the evening, because the caffeine can make it harder to get to sleep. If heartburn keeps you awake, see heartburn during pregnancy.

Can you sleep on your stomach while pregnant?

You can sleep on your stomach in early pregnancy. The NHS says it is fine in the early days, because your bump will not start showing until the second trimester and lying on your stomach is unlikely to be uncomfortable. Dr. Srisuro says you can sleep on your belly, but you will reach a point where it is just not possible.

When should you call your doctor or midwife?

• Fewer movements or a change in their pattern. The NHS says this may be the first sign that your baby is unwell and to contact your midwife or local maternity unit immediately. When your baby's movements slow down has more.
• Lack of sleep that is bothering you. The NHS says to talk to your partner, a friend, your doctor or your midwife.
• Sleeplessness together with feeling hopeless or losing interest in things you used to enjoy. The NHS says to speak to your doctor or midwife, because these can be signs of depression and there is treatment that can help.