My hips have been hurting me so bad I've had 2 resort 2 my back also...we r suppose 2 lay on our sides...The left side mainly...so baby can get adequate amts of oxygen but like hobojo said I slept on my back w other 2 & they came out fine
I did that with my first i didnt wanna lay any way but on my back it was the only thing that felt good, she came out just fine. I never was told i couldn't do it... so :/ i dont see anything wrong with it