Your baby’s head shape may be abnormal at birth or become abnormal over the first several months of life. A flat spot on the back of the baby’s head is almost always due to pressure on the head in the uterus, if present at birth, or pressure from lying on the back with the same side of the head always down, causing a flat spot after birth. This occipital flat spot or asymmetry is called by a number of different names including benign positional molding
It is important that babies sleep on their backs as this simple manuever has reduced the incidence of sudden infant death syndrome by 40%. But the number of babies developing flat spots on the back of their head has increased.
I’ll go over how to prevent the flat spot from developing or treat it if it does develop.
But the first thing that your doctor will do is to make sure the flat spot isn’t from another very rare condition called lamboidal craniosynostosis. Lamboidal craniosynostosis (LC) is due to the abnormal fusion of two of the skull bones and it won’t respond to simple treatment. LC occurs in only 3 out of 100,000 infants. It is diagnosed by skull radiographs or CT scan but again is so rare that these tests will not often be needed.
Sometimes a neck muscle problem called torticollis can cause the infant to always have one side of his head down. Your doctor can diagnose this by assessing the child’s neck movement with the rotating stool test. If your child has torticollis the doctor will prescribe some neck exercises you can do each time you change the baby’s diaper.
If your baby is born with a flat spot on the back of his head or develops one there is simple treatment available. When you put the baby down to sleep, again always on his back, be sure to alternate his head position so that one side is down one sleep session and the other side is down the next sleep session.
Also don’t have the child sit in his car seat except when he is in the car as using the car seat at other times can worsen the flat spot. The baby should spend time on his stomach when he is awake and you are able to watch him.
The doctor will monitor the baby’s head shape which should improve with the above. If it does not, or if it worsens the doctor will refer the infant to a pediatric neurosurgeon for consideration of a skull molding helmet and to make sure that the child doesn’t have the very rare lamboidal craniosynostosis. The best response to the helmets occurs in 4 month to 12 month period. Craniosynostosis almost always requires surgery. In very rare cases surgery is needed in benign positional molding.
The American Academy of Pediatrics “Prevention and Management of Positional Skull Deformities in Infants is available at https://aappolicy.aappublications.org/cgi/reprint/pediatrics;112/1/199.pdf