Flat head syndrome is a condition where a baby’s head develops an abnormally flat shape. It is usually on the back or side of the baby’s head. This condition is also called plagiocephaly (Pronounced play-jee-oh-sef-uh-lee)
Baby’s head are relatively soft after birth. Placing your baby on one side or on baby’s back for prolonged periods of time can exert pressure on that side of the skull and cause it to be flat. The frequency of this cause of flat head has increased following the ‘back to sleep’ campaign.1 The other reason for flat head is early fusion of the connecting sutures in a baby’s skull bone. The connecting sutures should not be fused until after a few months. If they fuse earlier than they should, this could cause an abnormally shaped head.
Reference: 1. Turk AE, McCarthy JG, Thorne CH, Wisoff JH. The "back to sleep campaign" and deformational plagiocephaly: is there cause for concern? J Craniofac Surg 1996; 7:12.