Causes of Plagiocephaly
The most common cause of a flattened head is a
baby's sleep position. Infants are frequently left
in a position where the head is resting against a
flat surface, such as in cribs, strollers, swings,
and playpens. Because infants' heads are soft to
allow for the incredible brain growth that occurs
in the first year of life, they're susceptible to
being "molded" into a flat shape.
Premature babies are more prone to positional plagiocephaly because their skulls are softer than those of full-term babies, and they spend a great deal of time on their backs without being moved or picked up. This is because of their medical needs and extreme fragility after birth, which usually requires a stay in the neonatal intensive care unit.
Another thing that can contribute to flattening is torticollis, which means the neck muscles are too tight, have inadequate tone, or are shorter on one side than the other, causing the head to tilt one way while the chin points in the opposite direction.
A baby may even start to develop positional plagiocephaly before birth, if pressure is placed on the baby's skull by the mother's pelvis or a twin. In fact, it's not at all unusual to see plagiocephaly in multiple birth infants.
But the differences in head shape seen in children with positional plagiocephaly shouldn't be confused with those caused by craniosynostosis, a more serious condition that occurs when skull bones fuse together too soon, causing an abnormal skull shape and possible brain damage. A child with craniosynostosis may have deformities in the front of the head and a bony ridge over the abnormally fused skull bones.