It's called plagiocephaly, fancy name for a flat spot on the back of the head due to postion. Sometimes it's caused from postion in the mothers womb, but can also happen after birth. Preemies are more prone to it due to be on their backs in the NICU with vents, cpap, tubes, etc.
It usually corrects itself as they get older. Try to keep them off of that side when they go to bed and switch their crib to the other side of the room.
Sometimes they can develop toritcollis, meaning that the muscles in the side of the neck are too weak. Preventing the infant to turn his/her head to the other side.
In severe cases a helmet or band can be fitted for the baby's head to help correct the postion. This should be done before 9 months to be the most effective. They are fairly expensive though.
Jack has this conidtion and it's severe....but he cannot have a helmet or band because he has external hydroceplaus as well as the history of his brain bleed. Putting this on his head would cause Inter crainal pressure and he would be in more trouble.
We do physical therapy at home to help Jack delevlop stronger neck muscles and we're trying to correct his flat spot.
His will always be there b/c it's pretty severe. ...but it's okay I can deal with it.