JAMA Pediatrics - Flat He...

Flat head syndrome is caused by prolonged pressure on an infant’s skull during pregnancy or early infancy.

There are 2 types of flat head shapes, although some infants can have both forms. In plagiocephaly, the back of the head is flat on one side. In severe cases, this may cause the ear on that side of the head to appear pushed forward and/or lead to an uneven appearance of the face, neck, or jaw. In brachycephaly, the back of the head is flat and the head appears wider than normal.

Flat head syndrome does not affect brain development or intelligence. Approximately 1 in every 8 healthy infants younger than 1 year have flat head syndrome, although most have a mild form. Diagnosis is made by a clinician based on physical examination.