Merck Manual

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Cytomegalovirus (CMV) Infection in Newborns

(Congenital Cytomegalovirus Infection; Perinatal Cytomegalovirus Infection)


Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Jul 2020| Content last modified Jul 2020
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Cytomegalovirus is a common virus that usually causes few or no problems but can cause serious illness in infants who are infected before birth or around the time of birth.

  • Cytomegalovirus infection is caused by a virus.

  • Most newborns do not have symptoms, but some do depending on when they were infected.

  • Doctors diagnose the infection by identifying the virus in a sample of urine, saliva, blood, or tissue.

  • Newborns may develop neurologic problems such as hearing loss.

  • Handwashing can help prevent spread of the virus.

  • Cytomegalovirus infection cannot be cured, but some antiviral drugs can limit the problems caused by infection.

Pregnant women may acquire cytomegalovirus (CMV) easily through contact with infected people.

When a baby contracts CMV infection in the uterus, it is called congenital CMV infection. When a baby develops the infection immediately before, during, or shortly after birth, it is called perinatal CMV infection. CMV infection is the most common congenital viral infection.

A woman can pass the virus to her fetus during pregnancy if the virus crosses the placenta (the organ that provides nourishment to the fetus) and infects the fetus. The infection in the woman during pregnancy may be a first-time infection or the reactivation of a previous infection (CMV can remain in the body in an inactive state). The woman may not have any symptoms.

Newborns may also become infected during passage through the birth canal, through breast milk containing the virus, or through a contaminated blood transfusion.

Premature infants are at higher risk of developing symptoms from CMV infection because they are less likely to have protective antibodies from their mother.

CMV infection may cause problems in newborns depending on whether they were infected before or after birth.


Of newborns who are infected with CMV before birth, only about 10% have symptoms.

In newborns infected before birth, possible symptoms include

  • Low birth weight

  • Jaundice (yellow skin)

  • Small bruises in the skin

  • An enlarged liver and spleen

  • Inflammation of the lungs or eyes

In newborns infected during or after birth, possible symptoms include

Some newborns have all of these symptoms.


  • Testing of urine, saliva, or tissue samples

  • Polymerase chain reaction (PCR) test using urine, saliva, blood, or tissues

To diagnose CMV infection, doctors take samples of the newborn's urine, saliva, or tissues. The samples are sent to a laboratory so the organism causing the infection can be identified.

Doctors also do a PCR test on samples of the newborn's urine, saliva, blood, or tissues. This laboratory technique, which produces many copies of a gene to make the gene easier to detect, can be used to detect the CMV virus in the DNA from the newborn.

Other tests are done to look for infection and inflammation and to determine the seriousness of the symptoms. Doctors may do other tests to rule out other infections present at birth that cause symptoms similar to CMV.


A significant percentage of CMV-infected newborns who have symptoms die. Most of those who survive will have some neurologic problems, including

About 5 to 15% of newborns who do not have symptoms eventually develop neurologic problems, but they are typically mild compared to the problems developed by newborns who have symptoms. Some degree of hearing loss is the most common.


Pregnant women should try to limit their exposure to the virus. For example, because CMV infection is common among children attending day care centers and easily spread, pregnant women should always wash their hands thoroughly after exposure to urine and saliva from children in day care.


  • Ganciclovir or valganciclovir for newborns who have symptoms

There is no cure for CMV infection.

Ganciclovir and valganciclovir are drugs that combat certain viral infections (antiviral drugs) and may help relieve some symptoms.

Newborns should have repeated hearing tests during the first year of life.

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