Generally the older baby is the less of a problem it is. It all comes down to the strength of your own LO, can they lift their head, can they roll themselves over, can they kick covers away from face, etc...DD1 rolled onto her side to sleep from day dot (had MW exclaiming she hadn't put her down that way, :lol: ) whilst DD2 has always slept on her back & has yet to master rolling over.