Hehe Sal, no actually I did ask bout that one. Coz of my back/hip injury, I can't sleep on my side or stomach so advised my obgyn. His midwife said up to 30wks is fine, but on side thereafter, but then asked my obgyn, he said it is fine to lie on back right through, it doesn't hurt the baby at all. Only reason people say this is coz it can make u dizzy sleepin on ur back later on in pg & in that case, u'd prefer to lie on side.