I did at first, but slowly I've started migrating to my back. I had a friend who was sleeping on her stomach all the way to 37 weeks. If your body wants it and you don't have any negative or painful effects/feelings, you're totally fine. :)
I sleep on my belly all the time, it's the only way I can sleep. I'm 17 weeks
I sleep on my belly and back all the time because I've heard baby will send signs when it's time to move
I sleep on my side my Dr said sleeping on belly cuts off circulation
I sleepy mostly on my left side, but move a lot thru the night
I've heard sleeping on belly us fine, but to avoid sleeping on back because the weight of uterus can block one of the blood vessels. If I remember right, you don't have to worry about that until about week 20 when uterus is bigger.
My doctor said there are no proven facts that sleeping on the back is harmful. Your body will decide what's comfy!
Not comfortable with sleeping on my stomach but loves my right side