What is microcephaly in children?

Microcephaly is a condition where a baby's head is much smaller than normal. It is most often present at birth (congenital). Most children with microcephaly also have a small brain and an intellectual disability. Some children with small heads have normal intelligence.

What causes microcephaly in a child?

Microcephaly may be caused by problems during a woman’s pregnancy. These include:

  • Exposure to toxic chemicals
  • Methylmercury poisoning
  • Not enough vitamins and nutrients
  • Infection with cytomegalovirus, rubella, varicella virus, Zika virus, or toxoplasma
  • Prescription medicine use
  • Illegal drug use
  • Drinking alcohol
  • Untreated phenylketonuria
  • Stroke

In some cases, microcephaly may be caused by inheriting an abnormal gene. Microcephaly is an autosomal recessive gene disorder. Autosomal means that boys and girls are equally affected.  Recessive means that 2 copies of the gene, 1 from each parent, are needed to have the condition.

Some genetic disorders that cause microcephaly are X-linked. This means the faulty gene is on the X chromosome. Girls can have the faulty gene on 1 of their X chromosomes but not have any signs or symptoms of the disease. They are carriers for the condition. Boys only have one X chromosome. If their X chromosome carries a faulty gene they will have symptoms.

In some cases, microcephaly may occur after birth. This is known as acquired microcephaly. It can happen because of injury to the brain. This may be caused by lack of oxygen or an infection.

Which children are at risk for microcephaly?

A child is more at risk if he or she has a parent or sibling with microcephaly, or who carries a faulty gene.

A child is also more at risk if the mother has problems in pregnancy such as:

  • Exposure to toxic chemicals
  • Methylmercury poisoning
  • Not enough vitamins and nutrients
  • Infection with cytomegalovirus, rubella, varicella virus, Zika virus, or toxoplasma
  • Prescription medicine use
  • Illegal drug use
  • Drinking alcohol
  • Untreated phenylketonuria
  • Stroke

What are the symptoms of microcephaly in a child?

Symptoms can occur a bit differently in each child. They may include:

  • Very small head
  • High-pitched cry
  • Trouble feeding
  • Seizures
  • Shaky movement of the arms and legs (spasticity)
  • Developmental delays
  • Intellectual disability

The symptoms of microcephaly can be like other health conditions. Make sure your child sees his or her healthcare provider for a diagnosis.

How is microcephaly diagnosed in a child?

Microcephaly may be diagnosed before birth by prenatal ultrasound. This imaging test uses high-frequency sound waves and a computer to make images of blood vessels, tissues, and organs. Ultrasounds let healthcare providers see the internal organs as they function. They also show blood flow through blood vessels. In many cases, microcephaly may not be seen with ultrasound until the third trimester.

After birth, the healthcare provider will ask about your child’s health history. He or she may ask about your pregnancy and health history, and your family’s health history. The provider will give your child a physical exam.

Your child may have tests, such as:

  • Head circumference measurement. The measurement is compared with a scale for normal growth and size.
  • CT scan. This test uses a series of X-rays and a computer to create images of the inside of the body. A CT scan shows more detail than a regular X-ray.
  • MRI. This test uses large magnets, radio waves, and a computer to make images of the inside of the body.
  • Blood tests. These include genetic tests. Genetic tests check for conditions that tend to run in families.
  • Urine test. This is done to look for a substance that may show a certain type of microcephaly.

How is microcephaly treated in a child?

There is no treatment for microcephaly that will return the baby's head to a normal size or shape. Microcephaly is a lifelong condition that has no cure. Treatment focuses on preventing or reducing problems and maximizing a child's abilities.

The healthcare team will give support and teach you how best to manage your child’s health. Over time, your child may see healthcare providers such as:

  • Pediatrician or family doctor. This is a child’s primary healthcare provider.
  • Neurologist. This is a doctor who treats conditions of the brain, spinal cord, and nerves.
  • Rehabilitation team. These include physical, occupational, speech, and audiology therapists.

Talk with your child’s healthcare providers about the risks, benefits, and possible side effects of all treatments.

How can I help prevent microcephaly in my child?

Your healthcare provider may advise genetic counseling. You can learn more about the risk of microcephaly in a future pregnancy.

Parents who have 1 child with autosomal recessive microcephaly have a 1 in 4 (25%) chance for another child with microcephaly with each pregnancy. For X-linked microcephaly, mothers who are carriers have a 50% chance that a son will have the disorder. Daughters have a 50% chance of inheriting the gene and the same risk of passing it along to their children.

Also talk with your healthcare provider before and during pregnancy to minimize risks from:

  • Exposure to toxic chemicals
  • Methylmercury poisoning
  • Not enough vitamins and nutrients
  • Infection with cytomegalovirus, rubella, varicella virus, Zika virus, or toxoplasma
  • Prescription medicine use
  • Illegal drug use
  • Drinking alcohol
  • Untreated phenylketonuria
  • Stroke

How can I help my child live with microcephaly?

The full range of issues are usually not known right after birth. Issues can revealed as a child grows and develops. Children born with microcephaly need to see their healthcare team often. They will need tests to track the growth of the head. Their motor, social, intellectual, and language function will be tracked over time.

You can help your child strengthen his or her self-esteem and be as independent as possible. Your child may need physical and occupational rehabilitation. He or she may need extra support in school. The healthcare team will talk with you about the best ways to help your child.

When should I call my child’s healthcare provider?

Call the healthcare provider if your child has:

  • Symptoms that don’t get better, or get worse
  • New symptoms

Key points about microcephaly in children

  • Microcephaly is a condition where a baby's head is much smaller than normal. It is most often present at birth (congenital).
  • Most children with microcephaly also have a small brain and intellectual disability. Some children with small heads have normal intelligence.
  • Microcephaly may be caused by problems during a woman’s pregnancy. In some cases, it may be caused by inheriting an abnormal gene.
  • Microcephaly is a lifelong condition that has no cure. Treatment focuses on preventing or reducing problems and maximizing a child's abilities.
  • Children born with microcephaly need to see their healthcare team often. They will need tests to track the growth of the head. Their motor, social, intellectual, and language function will be tracked over time.
  • Your healthcare provider may advise genetic counseling. You can learn more about the risk for microcephaly in a future pregnancy.

Next steps

Tips to help you get the most from a visit to your child’s healthcare provider:

  • Know the reason for the visit and what you want to happen.
  • Before your visit, write down questions you want answered.
  • At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your provider gives you for your child.
  • Know why a new medicine or treatment is prescribed and how it will help your child. Also know what the side effects are.
  • Ask if your child’s condition can be treated in other ways.
  • Know why a test or procedure is recommended and what the results could mean.
  • Know what to expect if your child does not take the medicine or have the test or procedure.
  • If your child has a follow-up appointment, write down the date, time, and purpose for that visit.
  • Know how you can contact your child’s provider after office hours. This is important if your child becomes ill and you have questions or need advice.