I'm 15 weeks I still lay on my tummy. not for much longer but as long as you're comfortable you should be ok. you'll definitely feel it if you're cutting off any circulation.

If you're on your right side you can cut off circulation to an artery. Idk what it's called. they suggest left side after so many weeks

After a certain point laying straight on your back causes your uterus to press on the major vein that returns blood from the lower part of your body to your heart, and can also interfere with bloodflow to the placenta. Which is why sides are best

At 12 weeks you'd be fine to sleep on your back & belly as long as you're comfortable.

just sleep how ur comfortable. sleeping on ur belly is fine as long as its comfortable for u. at least that's what I've been told. and left side is preferable for circulation.

I've talked to two OBs and both said it's better to sleep any which way than to not sleep though. Left side is just how they would prefer in an ideal world and is not a make or break issue.

oh didn't know that

laying on your left side promotes healthy and stronger circulation ☺