i lay on my tum all the way through pregnancy with my DD but had to do some careful construction with pillows to keep myself comfy! i used to lay a double stack of pillows to make a triangle around my tummy! its apparently better to lie on your left side, better circulation plus theres nothing that baby will be lying on on that side, but who can lie still all night long anyway! i think as long as your comfy nd are managing to get some sleep then its fine!
this pregnancy i have been lying on my side, but i cant face OH has his breath makes me sick! (theres nothing wrong with it, he brushes, flosses and mouthwashes before bed) the sound and the feel of his breath on my face makes me feel sick, but next week we are moving the bed closer to the window so that we will have room to put a moss basket and chest of drawers on my side of the bed and we will be switching sides so that baby wont be near the window, so i should be lying on my left side then, i bet i end up being ridiculously uncomfortable! haha!