Lots of people claim that babies sleep better when they sleep on their tummies. I can't speak for all babies, but that was pretty much true for William. Once he was able to sleep on his stomach, he did. From then on, until he started sleeping in a big boy bed, his default sleep position was on his stomach. With his bottom in the air.
So awhile ago--I don't remember exactly when--Andrew started sleeping through the night. He's done it off and on for awhile, but then he started doing it fairly reliably a few weeks ago. Sure, we'd get one of those nights, here and there, when he'd need rebinking (read: re-insert the pacifier into mouth of squalling babe) a few times, but they were starting to decrease.
Then he started rolling over onto his tummy. Now his latest trick is to roll himself over onto his stomach, fall asleep, squirm around in his sleep, and then wake up on his stomach. He seems to have forgotten that he can roll back onto his back, so he thinks he's stuck. And oh, that makes him so mad! One night last week, I was jolted out of a sound sleep by the sound of frantic baby cries. I limped as fast as I could into Andrew's room, and there he was, on his stomach, sideways in the crib, with both leg hanging out between the slats. No wonder he was mad!
He's doing better again. He does seem to like sleeping on his stomach. Just not waking up on his stomach. So I'll be really glad when he remembers how to roll back onto his back without assistance again.