My fav position has always been on my back which you are not meant to whilst pg. I have found I am most comfortable with a pillow under one butt cheeck and one pillow wedged in under my belly on the other side and that way I can half sleep on my back. I tend to rotate butt cheeks and get a better night sleep this way (as better as it can be in between getting up 4-5 times for a wee!