After 6 months of religiously making sure DD sleeps on her back, she has started to roll over and sleep either on her front or on her side. She is in a wide cot bed but even so this usually means her face is pressed down close to the side bars. No cot bumper but I'm still a bit concerned, especially as she has a cold and so her breathing is not as easy as usual. Is it normal for babies to get to a point where they prefer not to do 'back sleeping'? Can I just assume if she's doing this herself it's OK, or should I be checking often to try and avoid it? It seems to happen usually in the last part of sleep from about 4am onwards.