What Is Microcephaly?

Microcephaly is a rare nervous system disorder that causes a baby's head to be small and not fully developed. The child's brain stops growing as it should. This can happen while the baby is still in the mother's womb or within the first few years of birth.

How Does a Baby Get Microcephaly?

Your doctor may not be able to tell you why this happened to your baby. In most cases, the exact cause is unknown.

It can be brought on by:

  • A problem with your genes (congenital microcephaly)
  • Something in your environment (acquired microcephaly)

Congenital microcephaly is passed down through families. It's caused by defects in genes linked to early brain development. Microcephaly is often seen in children with Down syndrome and genetic disorders.

Acquired microcephaly means the child's brain came into contact with something that harmed its growth and development. Some things that may do this while a baby is in the womb are:

Acquired microcephaly can also be caused by other things, including:

  • Hemorrhage or stroke in the newborn
  • Injury to the brain after birth
  • Spine or brain defects

How Does a Doctor Know a Baby Has This?

Your doctor may diagnose microcephaly before or after the baby is born.

During pregnancy, an ultrasound may show that the baby has a smaller-than-expected head size. To see this clearly, it's best to have the test at the end of your 2nd trimester or when you're entering your last 3 months of pregnancy.

After the baby is born, a health care worker will measure around the widest part of your child's head. The number is then marked on a growth chart. Doing this tells the doctor how your child's head is growing compared to other kids of the same age and sex. If your child's head measurement falls a certain point below the average, it's considered microcephaly.

A head measurement is taken during every checkup until age 2 or 3. If your child has microcephaly, the size of his head will be checked at every doctor's visit.

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What Symptoms Will a Child Have?

Children with a mild case may have a small head but no other problems. Your child's head will grow as he gets older. But it will remain smaller than what's considered normal.

Some children have normal intelligence. Others have problems learning, but they usually don't get worse as your child gets older.

Other symptoms may include:

  • Balance and coordination problems
  • Developmental delays (delayed sitting, standing, walking)
  • Trouble swallowing and problems with feeding
  • Hearing loss
  • Hyperactivity (trouble paying attention or sitting still)
  • Seizures
  • Short height
  • Speech problems
  • Vision problems

How Is Microcephaly Treated?

There's no cure for microcephaly, but there are treatments to help with development, behavior, and seizures.

If your child has mild microcephaly, he'll need regular doctor checkups to monitor how he grows and develops.

Children who have more severe cases need lifelong treatment to control symptoms. Some, like seizures, can be life-threatening. Your doctor will discuss treatments to keep your child safe and improve his quality of life.

Your child may need:

  • Medicines to control seizures and hyperactivity and to improve nerve and muscle function
  • Speech therapy
  • Physical and occupational therapy

What Are the Long-Term Effects?

How well your child does depends on what caused the brain to stop growing in the first place. Children with a mild form of this disorder may have no other problems. They grow normally during childhood and adolescence and still meet age-appropriate growth milestones as they get older.

Others can have severe problems with learning and moving. Children with microcephaly are more likely to have other medical problems, like cerebral palsy and epilepsy.

Can It Be Prevented?

While you're pregnant, you can take steps to try to prevent acquired microcephaly:

  • Eat a healthy diet and take prenatal vitamins.
  • Don't drink alcohol or do drugs.
  • Stay away from chemicals.
  • Wash your hands often, and get treated for any illness as soon as you feel sick.
  • Have someone else change the litter box. Cat feces can spread the parasite that causes toxoplasmosis.
  • Use insect repellent when in wooded areas or countries known for mosquitos. The CDC says insect repellent is safe to use while pregnant.

If you have a child with microcephaly and wish to get pregnant again, talk to your doctor. Genetic counseling may help you understand your family's risk for the disease.

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Where Can I Find Support?

Sometimes, talking to others in similar situations can help you better understand a disease or what to expect. The Foundation for Children with Microcephaly has a program that can put you in touch with other parents of a child with the disorder.

WebMD Medical Reference Reviewed by Dan Brennan, MD on January 19, 2016

Sources

SOURCES:

CDC: "Facts about Microcephaly."

National Institute of Neurological Disorders and Stroke: "NINDS Microcephaly Information Page."

Schuler-Faccini, L. Morbidity and Mortality Weekly Report, published online Jan. 29, 2016.

Foundation for Children with Microcephaly: "About Us."

Boom, J.A. "Microcephaly in infants and children: Etiology and evaluation."UpToDate, December 2015.

KidsHealth: "Growth Charts."

Minnesota Department of Health: "Microcephalus (also called microcephaly)."

Genetics Home Reference: "Autosomal recessive primary microcephaly."

News release, American Academy of Neurology, 2009.

Early Childhood Michigan: "Having A Healthy Pregnancy: ABC's...Pregnancy Tips (A-Z)."

CDC: "Zika Virus Prevention."

© 2016 WebMD, LLC. All rights reserved.

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