ive just reached 38 weeks and there is no way i can sleep on my back i get so jelous looking at partner sleeping he looks so comfy on his back and sleeping on his tummy!!! but since i ve gotten so big it really hurts to sleep on my back if i even lay on my back for 5mins it is so painfull i dont know if this is because i am already a mother with another on the way so my back aint quite as good as it used to be but i find it so funny you need like a pillow under your head one under your belly one inbetween your legs then one to cuddle. but like i said in the post at the start that is only information i have read who knows what is right and what is wrong if you followed everything you were ment to whilst being preg then you wouldnt be able to even get out of bed so do what feels right good luck with pregnecy everyone.