An infant’s skull is very soft to allow the brain to grow during the first year of life. If the head stays in the same position, a flat spot may develop.
Plagiocephaly can be caused by lying in one position too long with the head turned to only one side. This can happen in babies who sleep on their backs or spend a big part of the day in a baby car seat, bouncy seat, swing and/or stroller. The combination of sleeping on the back and pressure on the back of the baby’s head can create a flat spot.
Once the head changes begin, if the baby is not put in different positions, the flat spot may get worse.