Are you an avid back sleeper? You may want to get used to a new sleep position now, since you shouldn't sleep on your back after 20 weeks of pregnancy. When you lie belly-up, the weight of your uterus can compress a major blood vessel, called the vena cava. This disrupts blood flow to your baby and leaves you nauseated, dizzy, and short of breath.
Here are more tips for sleeping safely while pregnant:
The best way to sleep during the second half of pregnancy is on your side. Some doctors recommend the left side over the right because the vena cava is located to right of your spine, so sleeping on your left side allows blood to flow more freely to your baby. However, this shouldn't make a big difference, and it's more important that you pick whichever side feels better.
If you need help adjusting to side-sleeping, try supporting different parts of your body with a variety of pillows. One pillow between your knees and another below your hips can help you balance on your side more easily. Also test out sleeping with a full-body pillow placed behind your back or in front of you, or experiment with a wedge- shaped pillow, propping it under your side or chest.
Another tip: If you're waking up with aches, a firmer mattress might be the answer; a memory foam mattress supports your torso and limbs, and could make it easier to sleep in a position that is new to you.
Should you wake up on your back in the middle of the night, don't freak out. Your body would get dizzy and nauseous before your baby was in any real danger of not getting enough oxygen. By the time your uterus is heavy enough to compress the vein, you'll be so uncomfortable lying on your back that your body will flip over, even if you're asleep.
According to a 2017 study, researchers from the University of Auckland found that women who sleep on their backs during their third trimesters may also be putting undue stress on their fetuses—which might, in turn, increase stillbirth risk. A 2011 study that involved 500 pregnant women also suggested that sleeping in the supine position might increase risk of late stillbirth—though other pregnancy complications may have affected these results.
Sean Daneshmand, M.D., an Ob-Gyn and the founder of Miracle Babies, offers some reassurance. "This was a study on low-risk patients with a very small sample population without any difference in pregnancy complications or newborn outcomes," he says. "Given the very low incidence of stillbirths and the very high likelihood that majority of women can relate to falling asleep on their back at one or more times during their pregnancy, I do not think this is something of concern."
RELATED: How to Sleep When Pregnant