Im 18weeks now but pretty early on just the pressure of my husband's arm at night was uncomfortable. With that being said here and there I've managed to lay on my belly at 18 week without feeling any discomfort. The baby still kicks when i roll back over and seems to be fine. However I don't know for sure this is a good thing given a arm used to drive me crazy. How long could you sleep on you belly before it was impossible and do you believe 18w is where i should just quit trying to lay on mine at all?