DS slept better on his tummy... so I let him. If he's going to roll over anyway then he can roll back and you can't really stop it.

DS now prefers to sleep on his left side. I put him down21qwasz ON HIS BACK, HE wriggles onto his side and falls asleep. Some nights I hav to shift him over bcause he's bout to fall out of bed, but not often.