Since the recommendations for sleep positions changed and parents began putting infants to sleep on their backs to reduce their risk of SIDS, this problem has greatly increased.
Infants can also be at risk for positional plagiocephaly if they lay in a car seat, bouncy seat, or swing for too long. Alternatives, like a wrap, sling, or carrier, usually put less pressure on the back of a child's head and can be helpful in preventing flat head.
Although many infants develop positional plagiocephaly because they simply prefer to lie in one position all of the time, others have this problem because they have limited neck motion and can't help laying in the same position. These children, those with congenital torticollis, have limited motion on one side of their neck and may have a hard mass on their neck muscle.
Preventing Flat Head
Since posterior plagiocephaly is caused by too much pressure being put on one part of your infant's head, you can often prevent it from occurring by alternating the positions your infant stays in. This does not mean that you should stop putting your child to sleep on his back, but you can alternate the head position that he usually sleeps in.Spending more time on his stomach in 'tummy time' when he is awake (prone position) and being supervised is also a good idea. And try to avoid letting your infant spend a lot of time in the same position on his back when he is awake.

