my dr told me that you should sleep however you can get comfortable because if you were doing damage or restricting blood flow you wouldn't be comfortable.. i have heard its not suggested you sleep on your back so when i cant get comfortable on my side like someone else said i just pop a pillow under my hip that tilts me to the side... try not to worry too much (i know easier said than done) plenty of ppl whove had healthy babies that ive mentioned things like this too have never even heard of it before..