Cytomegalovirus (CMV) is a virus related to the herpes viruses. It is so common that up to 85% of adults in the United States have been infected at some point in their lives.

Usually, CMV is a mild disease that does not cause any serious problems in healthy children and adults. Most people get flu-like symptoms or cold-like symptoms for a few days, if they develop any symptoms at all. However, some people, including immune-compromised women and newborn babies of women infected with CMV during pregnancy, can have serious complications and even death.

Pregnant women infected with CMV for the first time during pregnancy can pass the virus to their unborn babies. The virus can also pass from mother to baby in vaginal secretions during delivery and in breast milk after birth. The virus can pass from person to person through blood, saliva, breast milk, and urine.

Up to 40% of babies born to women who are newly infected with CMV during pregnancy will become infected. Not all infected babies will have symptoms at birth.

Newborns with CMV are likely to be born early and weigh less. Other possible problems include a small brain (microcephaly) or other nervous system disorders that can cause seizures, deafness, mental retardation, or death. This infection can cause the liver and spleen to become larger than normal, as well as jaundice, and blood disorders. Newborns with CMV may have a rash that consists of small bruises called petechiae and larger bruises known as purpura. Some of these findings can be detected with ultrasound, but most cannot.

A baby born to a mother who was already infected with CMV before she became pregnant is less likely to be born with CMV due to some preexisting immunity. Only 0.5% to 1.5% of such babies are infected (compared to 40% of babies born to mothers who were infected during pregnancy), and their problems tend to be less severe.

There are currently no treatments for maternal or fetal CMV infection.

The pediatrician may order blood tests for babies with low birth weight, jaundice, small brains, or other problems that can be associated with congenital CMV. The diagnosis needs to be confirmed by testing blood or tissue from the infant within three weeks of birth to be accurate.

Young, healthy pregnant women usually do not need to be tested because they do not need to be treated specifically for CMV. They usually recover over a period of weeks. In some instances, blood tests may be done to confirm the cause of the illness, since similar symptoms can be caused by the Epstein-Barr virus (EBV) and even human immunodeficiency virus (HIV). Some of the antibody tests used to test for CMV have a high false-positive rate and the testing needs to be repeated to be reliable.

Pregnant women who care for young children should take these precautions to reduce the risk of CMV:

  • Wash hands often with soap and water, especially after changing diapers. Wash well for 15 to 20 seconds.
  • Do not kiss young children under the age of five or six on the mouth or cheek. Instead, kiss them on the head or give them a big hug.
  • Do not share food, drinks, or utensils (spoons, forks, or knives) with young children.

If you are pregnant and work in a daycare center, reduce your risk of getting CMV by working with children who are older than two and a half years of age, especially if you have never been infected with CMV or are unsure if you have been exposed.