What Is Microcephaly?

Learn about symptoms, causes, treatment, and more

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Microcephaly is a congenital condition, which means it is present at birth, in which a baby’s head is significantly smaller than expected for an infant of the same age and gender.

Microcephaly Symptoms
Illustration by JR Bee, Verywell​

During a typical pregnancy, the head of the fetus grows as the brain grows. In microcephaly, often times the brain has not grown and developed properly, so the head has not grown accordingly, either.

Microcephaly is fairly rare, with the incidence ranging from 2 to 12 babies per 10,000 live births in the United States.


Although symptoms of microcephaly can vary, there are symptoms that are more common than others, including:

  • Very small-looking head
  • High-pitched cry
  • Feeding issues
  • Seizures
  • Developmental delays
  • Intellectual disabilities
  • Spasticity of the arms and legs
  • Vision problems
  • Movement and balance issues
  • Hearing loss

Children without microcephaly can have these symptoms, as well, so if you notice any symptoms that seem questionable or concerning, it’s best to call your pediatrician.

The severity of microcephaly can vary widely, as can the resulting symptoms, which is why a doctor would need to do a thorough examination of your child, along with any recommended tests, in order to come to a diagnosis.


In most babies, the cause of microcephaly isn’t known. For some babies, the cause might be genetic, while for others, it could be from prenatal exposure to a substance.

Possible causes of microcephaly might include:

  • Exposure to chemicals while in the womb
  • Lack of proper vitamins or nutrients in the maternal diet
  • Maternal drug and alcohol use during pregnancy
  • Untreated phenylketonuria
  • Interruption of blood supply to fetal brain while in the womb
  • Maternal infection during pregnancy of rubella, toxoplasmosis, or cytomegalovirus

The Centers for Disease Control and Prevention (CDC) has also stated that infection with the zika virus has caused babies to be born with microcephaly.

If you’re concerned about the risks of microcephaly, talk with your doctor about steps to take to reduce your risk of your baby developing microcephaly.


Sometimes microcephaly can be diagnosed while the baby is still in utero, through ultrasound, during the end of the second trimester or beginning of the third. Once the baby is born, physical examinations might yield a head measurement that is smaller than expected, or developmental delays might arise that warrant further examination in older children.

In babies and toddlers, doctors will measure the circumference of your child’s head at each visit and compare to a standardized scale of typical and atypical ranges.

Diagnostic tests that can be used to help diagnose or confirm microcephaly and brain abnormalities can include:

  • Head circumference measurement
  • Head ultrasounds
  • CT scan – uses X-rays and computer technology to get detailed images of bones, tissues, and organs
  • MRI – imaging technique to get images of organs and body structures
  • Blood tests
  • Urine tests


Microcephaly is a lifelong condition that cannot be cured or fixed, in the sense that the head will be able to be made into a typical size or shape.

Treatment focuses on minimizing and preventing further deformities, taking into account any developmental or cognitive delays or disabilities, and helping the child maximize their potential and capabilities.

This happens over time as the child gets older and the extent of any delays or disabilities are found. Depending on the severity of the microcephaly and any accompanying delays, appropriate treatment can include speech, occupational therapy, or medication.

After a child is diagnosed with microcephaly, they will be frequently tested and examined by different kinds of doctors. Their treatment team will be able to work with you to provide a treatment plan tailored to your child’s needs and abilities, and goals you’d like to accomplish.

If there is a genetic component to the microcephaly and you’re thinking of having more children, you might be recommended to work with a genetic counselor to get information and evaluate your risk of having another child with the condition.

A Word From Verywell

If your baby has been diagnosed with microcephaly, take a deep breath. While it’s not curable, there are therapies and treatments that can be done to minimize the effects of the condition and help your child maximize their abilities.

Talk with your pediatrician and the treatment team to find out more about the aspects of microcephaly that are specific to your child. Knowing about your child’s condition will help empower you to be part of the treatment team and act in their best interest.

Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  • Centers for Disease Control and Prevention. Facts About Microcephaly. 2017 

  • Stanford Children’s Health. Microcephaly. 2018. 

By Jaime R. Herndon, MS, MPH
Jaime Rochelle Herndon, MS, MPH, MFA, is a former writer for Verywell Family covering fertility, pregnancy, birth, and parenting.