Macrocephaly/how large is the head?

Macrocephaly. Macrocephaly is diagnosed when the circumference of the head is more than two standard deviations above average for the child's age, sex, race, and period of gestation and may be caused by many conditions. Macrocephaly would be the diagnosis if the ofc (occipito-frontal circumference) is >90%ile for his age and gestation.