If you are a back sleeper, you may have heard that sleeping on your back is a pregnancy no-no. Naturally, you may be worried, especially if you wake to find that you have spent most of the night on your back. Turns out, sleeping on your back is fine during the first and second trimesters. However, back sleeping needs is not safe during the third trimester. This is because lying on your back increases your risk of reducing blood flow to the uterus, which can cause serious complications, including stillbirth. “Sleeping on your back during pregnancy should be avoided in the third trimester to avoid compression of the vein that returns blood to the heart,” says Kim Langdon, MD, an Ohio-based OB/GYN with more than 20 years of experience. Learn more about when it’s safe to sleep on your back in pregnancy—and when it’s not.
Sleeping on Your Back During Pregnancy
Previous studies indicated that sleeping on your back during pregnancy puts you at risk of preeclampsia and your baby at risk of low birth weight, reduced fetal growth, and stillbirth. However, the latest research says that sleep position is not an issue during the first 28 weeks of pregnancy. When the baby, placenta, and uterine fluid grow heavier, sleep position becomes an important consideration. As you get closer to the third trimester, this weight may compress important blood vessels, leading to problems like low birth weight, preeclampsia, reduced fetal growth, and stillbirth. The weight of the contents of your uterus is what determines when back sleeping becomes unsafe. This may vary from person to person, so you should always talk with your healthcare provider to understand exactly when and whether back sleeping is safe for you and your specific pregnancy. Around 28 weeks gestation, choose a sleeping position other than supine. But if you do wake up on your back, just resettle yourself on your side or stomach.
Is It Safe for Baby?
Back sleeping during the first 28 weeks of pregnancy will not likely impact your baby. After about 28 weeks, sleeping on your back may increase the baby’s risk of being born at low birth weight due to reduced fetal growth, or stillbirth.
Why You Should Not Sleep On Your Back Past 28 Weeks
Lying on your back during pregnancy becomes problematic when your uterus becomes heavier, around 28 weeks. The contents of your uterus, which includes your baby, the placenta, and amniotic fluid, make up about a third of your pregnancy weight gain. When you lie in the supine position, the weight of your uterus falls upon a vein called the inferior vena cava. The inferior vena cava returns blood from the abdomen to the heart. Compressing this vein may lead to low birth weight, preeclampsia, reduced fetal growth, and stillbirth.
Risks of Sleeping On Your Back Past 28 Weeks Gestation
There are a few risks to be aware of when it comes to sleeping on your back later on in pregnancy. Here are some of the risks associated with sleeping in a supine position.
Preeclampsia
Too much pressure on the vena cava may increase your risk of developing preeclampsia, high blood pressure during pregnancy. With preeclampsia, you may experience headaches or abdominal pain, and your baby is at risk of preterm delivery or stillbirth.
Reduced Fetal Growth and Low Birthweight
Sleeping on your back past 30 weeks gestation can compress the inferior vena cava, potentially restricting blood flow, leading to reduced fetal growth. Reduced fetal growth also may result in low birth weight, which is defined as less than 5 pounds, 8 ounces. Babies born at low birth weight face increased risks, including breathing problems and jaundice.
Stillbirth
Studies found a threefold increase in stillbirth risk when pregnant people slept on their back after 28 weeks gestation. Back sleeping increases the risk of fetal growth restriction and fetal stress, both of which contribute to the risk of stillbirth. If comorbidities are present, these factors further increase the risk of stillbirth.
When Can I Resume Sleeping on My Back?
If you prefer to sleep in the supine position, it is fine to resume doing so after you give birth. When you deliver your baby and placenta, the vast majority of the weight in your uterus exits your body. Then, you no longer have the issue of compressing the vena cava to worry about. And once your baby is dozing in a bassinet, your sleeping position will not affect their development.
Pregnancy-Safe Alternatives
Back sleeping is no longer safe after 28 weeks gestation, but there are a few other comfortable positions for you to safely doze in.
Belly Sleeping
Sleeping on your stomach does not put pressure on any major blood vessels and is considered safe for your baby. Using a donut pillow like a Boppy may help you rest comfortably in this position.
Lateral Decubitus Position
If you sleep best on your back, sleeping almost on your back but not quite might be your most comfortable option towards the third trimester. “A good position for sleeping while pregnant is what the medical community calls the lateral decubitus position,” notes Alan Lindemann, MD, an obstetrician and maternal mortality expert and co-author of “Modern Medicine: What You’re Dying to Know,” a consumer action guide about how to navigate the United States healthcare system. “This position is halfway between flat on your back and totally on your side.” Pillows and bolsters may help you get into this position and stay in it while you sleep. When reclining in the lateral decubitus position, you can be on either side. “The important point is to not be fully on your side or fully on your back,” explains Dr. Lindemann.
Left Side Sleeping
After 28 weeks gestation, sleeping on your right side may have similar risks to sleeping on your back because this position can compress the aorta, a major artery. Sleeping on your left side is a safe alternative.
A Word From Verywell
Sleeping on your back during pregnancy is safe during the first two trimesters. During the third trimester, it is best to avoid back sleeping because it has been associated with some risks to both you and your baby. If you wake to find yourself sleeping on your back, simply reposition yourself. You also can place a pregnancy pillow behind your back to keep you from rolling into that position. Talk to a healthcare provider if you have any questions or concerns about sleep positions during pregnancy.
