Microcephaly is the medical term for having an abnormally small skull. This condition is usually, but not always, associated with mental retardation; however, it is often a sign that the brain is not developing normally.

This condition is often a symptom of various genetic and congenital disorders such as Edward's syndrome, Down's syndrome, Cri-du-chat, Xeroderma Pigmentosum, etc. It can also be caused when the pregnant mother catches diseases like rubella and toxoplasmosis.

Sometimes, though, infants under the age of 2 can develop the microcephaly after birth. Some causes of neonatal microcephaly include the baby becoming infected with herpes at birth or contracting meningitis.