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Colorado Fetal Care Center


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What is microcephaly? 

Microcephaly means a baby’s head is smaller than expected compared to other babies of the same sex and age. Doctors may diagnose microcephaly before a baby is born, at birth or later. It is rare, affecting an estimated one in 800 to 5,000 babies in the United States. 

Babies with microcephaly do not always have problems with development and brain function, but microcephaly does increase risk of these issues. Because of this risk, doctors work to identify microcephaly early. Early diagnosis can help ensure children receive care that helps them maximize their physical and intellectual function.

What causes microcephaly?

Doctors do not always know the exact cause of microcephaly. Some potential causes include:

  • Early joining of an infant’s skull bones (craniosynostosis)
  • Irregular fetal brain development
  • Fetal exposure to toxic chemicals, drugs or alcohol
  • Gene mutations (changes) or genetic conditions such as Down syndrome or bone growth disorders
  • Infections during pregnancy, including Zika virus, rubella, chickenpox, toxoplasmosis or cytomegalovirus
  • Severe malnutrition during pregnancy

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