Several days ago we moved our DD out of her moses basket and into her cot and she's already mastered the art of rolling over, from back to front, but then gets stuck and can't roll back. I'm lying awake worrying that she's going to suffocate if I don't roll her back... She's in a sleeping bag and on a good mattress with a fitted sheet on it. I know that you can buy things to prevent babies from rolling, but if it's safe for her to roll I'd rather let her develop at her own pace. Should I be worried?