It's fine to sleep however you're most comfortable during pregnancy. It's unlikely you'll be able to sleep comfortably on your stomach as your belly grows, but you can sleep face down for as long as it suits you. That's why by mid-pregnancy, most pregnant women are sleeping on their side.
Besides, is it OK to sleep propped up on your back when pregnant?
It's (Probably) Safe to Sleep on Your Back While Pregnant. My third trimester in my second pregnancy was rough. The days were fine, but the nights were awful. The only remotely comfortable position was lying on my back, propped up with a couple of pillows.
Can I sleep on my back during the first trimester?
If you typically sleep on your back, it's safe to continue doing so through the first trimester. But as your uterus gets heavier around mid-pregnancy, it's best to choose another position. A pillow between your legs can also help make side sleeping more comfortable.
Is it safe to sleep on your back in the 3rd trimester?
Generally, women in their third trimester are encouraged not to sleep on their backs. When you are on your back, your heavy uterus can reduce blood flow to the uterus and fetus. Most women aren't comfortable lying flat on their backs during the third trimester anyway. Most experts recommend sleeping on your side.