Are you a back, side or stomach sleeper? Depending on how you normally snooze through the night, you might have to rethink your favorite position when you’re expecting. To prevent blocking blood flow to baby, experts recommend sleeping on your left side during pregnancy.
Not your favorite sleep position? Don’t worry. You won’t have to switch things up until you hit the second trimester. “Before 12 weeks, you can sleep any way you want,” says Sara Twogood, MD, an ob-gyn at the University of Southern California and founder of the postpartum care package service Après Push. “A lot of women have breast tenderness or sensitivity, so many aren’t comfortable sleeping on their stomachs early on. But it’s just discomfort—it won’t cause any harm.” As your pregnancy progresses, though, sleeping on your back and stomach can become uncomfortable quickly.
Here’s what you need to know about each common sleeping position throughout the course of your pregnancy:
Sleeping on Your Back During Pregnancy
Between 15 and 20 weeks gestation, the uterus starts becoming large enough to interfere with blood flow when you sleep on your back. It can compress the inferior vena cava (IVC), a large vein that runs up the right side of your vertebral column and carries deoxygenated blood from the lower and middle body to the heart. Back sleeping can also constrict the aorta, blocking off the main blood supply to your body and placenta. As a result, “Sleeping on your back can decrease the return of blood to the heart, so the mother may wake up feeling short of breath or as though her heart is racing,” says Amelia Henning, CNM, a staff midwife at Massachusetts General Hospital in Boston.
Sleeping on Your Stomach During Pregnancy
Sleeping on your stomach is fine in early pregnancy—but sooner or later you’ll have to turn over. “Generally, it’s okay until the belly is growing, which is between 16 and 18 weeks, depending on how big the belly gets and how quickly,” Henning says. Once your bump starts to show, stomach sleeping gets pretty uncomfortable for most women. But avoiding your tummy isn’t just about what feels good—it’s also for safety reasons. “Sleeping flat on your stomach has the same negative effects as sleeping on your back,” Twogood says, explaining that sleeping on your belly can cause your baby bump to move inside your stomach and press against the aorta and IVC.
Sleeping on Your Side During Pregnancy
Spending the night on your side—specifically the left side—is the best sleep position during pregnancy. “That’s to get all the weight of the uterus off the right side to optimize blood flow,” Twogood says. “It’s also for the comfort of the mom.” Sleeping on your right side can still compress the IVC and isn’t as safe as being on your left, but using pillows to prop up the uterus so it’s not sliding to the right side can sometimes be an option, she adds.
Of course, if you’ve been a back or tummy snoozer all your life, changing to your left side can be hard. “I fully recommend getting a pregnancy body pillow and getting it early,” Twogood says. “You want to optimize its use during pregnancy, playing with its positions and [exploring] how it can support you best. You can also use it under your legs to decrease any hip or leg pain during sleep.” If you still can’t comfortably make the switch to your side, use pillows to prop yourself into an incline. Sleeping on your back at a 45-degree tilt can prevent a lot of the compression.
It’s not uncommon to fall asleep on your left side and wake up in a totally different position. If you wake up on your back, don’t panic. “You probably weren’t there for very long,” Henning says, since your body adjusts to avoid uncomfortable sleep positions. “If you’re on your back and in the third trimester, it will compress the blood flow and make you feel bad quickly, so you’ll wake up and wouldn’t have been lying on your back long enough to compromise the blood flow to the baby.” If you continue to wake up on your back, stomach or right side and are worried about it, ask your partner to check on you, Twogood suggests. If they wake up and notice you on your back, they can gently move you back to your left side.
Updated October 2017