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Congenital CMV Infection

About one out of every 200 infants are born with congenital cytomegalovirus (CMV) infection. However, only about one in five infants with congenital CMV infection will have long-term health problems.

Transmission

A pregnant woman can pass CMV to her fetus following primary infection, reinfection with a different CMV strain, or reactivation of a previous infection during pregnancy.  The risk of transmission is greatest in the third trimester whereas risk of complications to the infant is greatest if infection occurs during the first trimester. Risk of transmission for primary infection is 30-40% in the first and second trimesters, and 40–70% in the third trimester.

Signs & Symptoms

Most infants with congenital CMV infection never have health problems. About 10% of infants with congenital CMV infection will have health problems that are apparent at birth, which include

  • Premature birth,
  • Liver, lung and spleen problems,
  • Low birth weight,
  • Microcephaly, and
  • Seizures.

About 40-60% of infants born with signs of congenital CMV infection at birth will have long-term health problems, such as

  • Hearing loss.
  • Vision loss.
  • Intellectual disability,
  • Microcephaly,
  • Lack of coordination,
  • Weakness or problems using muscles, and
  • Seizures.

Some infants without signs of congenital CMV infection at birth may later have hearing loss, but do not appear to have other long-term health problems. Hearing loss may be present at birth or may develop later in infants who passed their newborn hearing test. About 10-20% of infants with congenital CMV infection who have no signs at birth will have, or later develop, hearing loss.

Diagnosing Congenital CMV Infection

Congenital CMV infection is diagnosed by detection of CMV in the urine, saliva, blood, or other tissues within two to three weeks after birth. Only tests that detect CMV live virus (through viral culture) or CMV DNA (through polymerase chain reaction (PCR)) can be used to diagnose congenital CMV infection. Congenital CMV infection cannot be diagnosed using samples collected more than two to three weeks after birth because testing after this time cannot distinguish between congenital infection and an infection acquired during and after delivery.

Serological tests are not recommended for diagnosing congenital CMV infection. Maternal IgG antibodies pass through the placenta during pregnancy; thus, CMV IgG testing of infants may reflect maternal antibody status, and does not necessarily indicate infection in the infant. Maternal IgM antibodies do not cross the placenta and, thus, CMV IgM in the newborn would indicate congenital infection, but is only present in 25-40% of newborns with congenital infection.

For diagnosis of acquired CMV infection see Interpretation of Laboratory Tests.

Treatment and Management

  • Antiviral medications, such as ganciclovir or valganciclovir, may improve hearing and developmental outcomes in infants with symptoms of congenital CMV disease. Ganciclovir can have serious side effects, and has only been studied in infants with symptomatic congenital CMV disease. There is limited data on the effectiveness of ganciclovir or valganciclovir to treat infants with isolated hearing loss.
  • Any infant diagnosed with congenital CMV infection should have his or her hearing and vision tested regularly. Most infants with congenital CMV grow up healthy. However, if the child has delayed onset of hearing or vision problems, early detection may improve outcomes. To learn more, see this CDC website about hearing loss in children.

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