Well I was told I thought u could sleep hower untill it unconterble
I stopped sleeping on my belly around 13 Weeks it does cut off oxygen as does sleeping on your back after month 3 is over they really suggest only sleeping on your left side but that's for maximum oxygen supply to your baby..i sleep on either side cuz who the heck wants to only sleep on one side for a whole pregnancy lol makes the hips hurt :/
It's not supposed to be OK to sleep on your belly because it cuts off blood supply to the baby. That said, memory foam might let you put off changing your habits for at least a little while. Some guy invented a mattress that has an egg-shaped hole cut out of it for a pregnant woman's tummy, with slightly larger or smaller pads to put in it to adjust for her growth. Memory foam would be a little like that, at least at first. But I wouldn't go too long with it. It's one of the harder things about pregnancy, not being able to sleep on your stomach, but over the long haul it is a small sacrifice to be sure the baby is getting all it needs.
I'm soon to be 18 weeks. I sleep however I want.
Depends on how far you are and if it's comfortable for you.