Baby with bright eyes

Cytomegalovirus, or CMV, is a common virus that infects people of all ages. Once CMV is in a person’s body, it stays there for life and can reactivate. A person can also be reinfected with a different strain (variety) of the virus.

Most people infected with CMV show no signs or symptoms. That’s because a healthy person’s immune system usually keeps the virus from causing illness. However, CMV infection can cause serious health problems for unborn babies infected with the virus. These babies have congenital CMV.

Most babies with congenital CMV infection never show signs or have health problems. However, some babies may have health problems that are apparent at birth or that develop later during infancy or childhood.


Key Facts

  • Women can pass CMV to their baby during pregnancy. The virus can cross through the placenta and infect the baby.
  • CMV is the most common infectious cause of birth defects in the United States.
  • Most babies with congenital CMV infection never show signs or have health problems.
  • Some babies with signs of congenital CMV infection at birth may have long-term health problems, such as hearing loss.
  • Hearing loss caused by congenital CMV may be present at birth or develop later, and may progress with age.
  • Early diagnosis of congenital CMV and treatment may help children develop to their full potential.


Prevention Tips

  • Pregnant women may be able to lessen their risk of getting CMV by reducing contact with saliva and urine from babies and young children. The saliva and urine of children with CMV have high amounts of the virus. A pregnant woman can avoid getting a child’s saliva in her mouth by, for example, not sharing food, utensils, or cups with a child. Also, she should wash her hands after changing diapers. These cannot eliminate her risk of getting CMV, but may lessen the chances of getting it.
  • Medicines called antivirals may decrease the risk of health problems and hearing loss in some infected babies who show signs of congenital CMV infection at birth.
  • Babies with congenital CMV infection, with or without signs at birth, should have regular hearing checks.

More Information

Page last reviewed: June 2, 2021