Microcephaly describes a head size significantly below normal for a person's age and sex, based on standardized charts. Head size is measured as the distance around the top of the head.

Microcephaly most often occurs because of failure of the brain to grow at a normal rate. Skull growth is determined by brain expansion, which takes place during the normal growth of the brain during pregnancy and infancy.

Conditions that affect brain growth can cause microcephaly, including infections, genetic disorders, and severe malnutrition.

Primary Causes:

• Cornelia de Lange syndrome
• Cri du chat syndrome
• Down syndrome
• Rubinstein-Taybi syndrome
• Seckel syndrome
• Smith-Lemli-Opitz syndrome
• Trisomy 13
• Trisomy 18

Secondary Causes:

• Uncontrolled phenylketonuria (PKU) in the mother
• Methylmercury poisoning
• Congenital rubella
• Congenital toxoplasmosis
• Congenital CMV
• Use of certain drugs during pregnancy
• Malnutrition

There are no specific home care procedures for microcephaly. Care depends on the condition that caused the microcephaly.

Microcephaly is often diagnosed at birth or during routine well-baby examinations when the infant's height, weight, and head circumference is measured. If you suspect your infant's head size is too small or not growing normally, consult your health care provider.

This finding is usually discovered by the health care provider during routine examination. Head measurements are a routine procedure during a well-baby examination up to 18 months (longer in certain circumstances). They are painless and take only a few seconds while the measuring tape is placed around the infant's head.

Documenting microcephaly in detail may include:

• What is the head circumference?
• Is the head growing at a slower rate than the body?
• What other symptoms are also present?

Note: A record of the head circumference should be maintained over time.

Although the health care provider maintains records on your baby, it may be helpful to maintain your own records of the well-baby findings, and to bring your records to the health care provider's attention if you notice that the infant's head growth pattern seems to be decreasing.

If a diagnosis was made by your health care provider related to microcephaly, you may want to note that diagnosis in your child's personal medical record.