Microcephaly is a condition that causes your baby’s head to be smaller than expected. Your baby can be born with a small head or this can become more apparent as they grow. Your baby could have no additional symptoms or the condition can affect their ability to learn and meet developmental milestones for their age. Supportive care and monitoring are important.


A baby with microcephaly, or a head that’s smaller than expected for their age.
Microcephaly causes your baby’s head to be smaller than expected.

What is microcephaly?

Microcephaly is a condition that causes your baby’s head to be smaller than expected for their size and age. Microcephaly happens when your baby’s brain needs more time to grow or doesn’t develop completely. The size of your baby’s skull depends on the size of their brain. Brain growth happens during fetal development and infancy.

What are the types of microcephaly?

There are two types of microcephaly:

  • Primary or congenital: Your baby is born with a smaller head.
  • Secondary or acquired: The condition develops as your baby gets older.

How common is microcephaly?

Microcephaly is rare. Research estimates it affects about 1 in every 800 to 5,000 babies in the United States.


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Symptoms and Causes

What are the symptoms of microcephaly?

A small head is the main symptom of microcephaly. The size of your brain influences the size of your head.

Growth abnormalities of the brain can affect how your baby’s brain functions, which can cause additional symptoms. These range in severity and can include:

  • Seizures.
  • Issues with cognitive development.
  • Developmental delays (learning how to speak, stand and walk).
  • Balance, movement and coordination challenges.
  • Difficulty feeding or swallowing.
  • Hearing or vision loss.

Symptoms can be life-threatening if they’re severe. Some babies have no symptoms other than a small head.

How does microcephaly affect my child’s physical growth?

As your child grows older, their face continues to grow while their skull doesn’t. This can cause your child to develop a large face in comparison to their head size. In addition, they may experience:

  • A receding forehead.
  • A loose, wrinkled scalp.
  • Less than expected weight for their age.

What causes microcephaly?

A lack of brain growth or changes to how your child’s brain grows can cause microcephaly.

Some causes of microcephaly include:

What are the risk factors for microcephaly?

Your child may be more at risk of developing microcephaly if they had exposure to the following during fetal development:


What are the complications of microcephaly?

Microcephaly can be life-threatening if symptoms are severe. It’s difficult to predict how the abnormal development of your child’s brain will affect their growth, so they may need lifelong support and monitoring to prevent complications.

Diagnosis and Tests

How is microcephaly diagnosed?

A healthcare provider can sometimes diagnose microcephaly before birth by prenatal ultrasound. This diagnosis, with the fetus still in the uterus, happens late in the second trimester or the third trimester.

A diagnosis most often happens within 24 hours after your baby is born. A healthcare provider will measure your baby’s head circumference (all the way around). Then, they’ll compare your baby’s measurement to growth standards for their age, which takes into account your baby’s length and weight.

If your baby has acquired microcephaly, a healthcare provider will diagnose the condition in infancy when symptoms become apparent. During a physical exam, your baby’s healthcare provider will measure your child’s head circumference. They may ask questions about your child’s progress in reaching developmental milestones for their age, like crawling or walking.

What is a head circumference percentile?

A percentile is a number on a scale of 1 to 100 that shows how a person compares to others. Percentiles help healthcare providers diagnose certain conditions. To receive a microcephaly diagnosis, your baby's head circumference must be in the 3rd percentile or lower. A head circumference in the 3rd percentile means 3% of all infants have a smaller head size, and 97% have a larger head size.

What tests diagnose microcephaly?

If your child’s healthcare provider suspects microcephaly, they’ll measure your child’s head circumference and run tests to determine the cause. Tests could include:

  • Imaging tests like a head ultrasound or brain MRI.
  • Blood tests to detect changes to their genetic code or any underlying conditions.


Management and Treatment

How is microcephaly treated?

Treatment for microcephaly focuses on managing symptoms of the condition and could include:

  • Management of any underlying health conditions.
  • Developmental services to help your child reach physical and learning milestones for their age.
  • Speech, occupational and physical therapies.
  • Educational support programs in school.
  • Medications to treat seizures.

Are there side effects of the treatment?

Before your child begins treatment, talk to their healthcare provider about the possible side effects, especially if they’re starting a new medication. Your child’s provider can walk you through what to look out for.


Can microcephaly be prevented?

You can reduce your child’s risk of microcephaly by taking care of yourself during pregnancy. This could include:

  • Eating a well-balanced diet.
  • Managing any underlying health conditions.
  • Avoiding toxic chemicals or substances.
  • Going to checkups regularly to monitor the development of the fetus.

Talk to your healthcare provider about ways that you can stay healthy during pregnancy.

Outlook / Prognosis

What can I expect if my child has microcephaly?

While there’s no cure for microcephaly, treatment is available to help your child manage any symptoms. Providers usually don’t know the extent of microcephaly until your child grows and develops. Their healthcare provider will monitor them through infancy and childhood to make sure there aren’t any complications.

Your child’s care team will usually consist of pediatricians, neurologists and therapists who can provide treatment, education and guidance to improve their health and well-being.

What is the life expectancy for microcephaly?

The prognosis depends on the severity of the condition. In some cases, a child won’t have complications and will have a normal life expectancy. More severe cases can reduce your child’s life expectancy. Their risk is higher if the condition affects their brain function.

Living With

When should my child see a healthcare provider?

Visit your child’s healthcare provider if they:

  • Miss developmental milestones for their age.
  • Don’t respond to their name or simple commands.
  • Have trouble eating or swallowing.
  • Don’t follow you or an object with their eyes.

Contact 911 or your local emergency services number if your child has a seizure.

What questions should I ask my doctor?

  • Does my child have severe microcephaly?
  • How will this condition affect my child’s development?
  • Should I enroll my child in educational programs to help them learn?
  • Are there side effects to the medications you prescribe?
  • Are there signs of complications I should look out for?

A note from Cleveland Clinic

Microcephaly is a condition that causes your baby’s head to be smaller than expected. It can be concerning to learn that your baby’s head is smaller than expected. Your baby’s healthcare provider and care team will monitor your baby’s development and provide services to help them. Contact your child’s provider if they miss milestones for their age, like walking and saying their first words. Early intervention can help your child as they grow.

Medically Reviewed

Last reviewed on 04/17/2023.

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