CMV in Pregnancy Health Article

What Do I Have?

Cytomegalovirus (CMV) is a DNA virus, part of the herpes family. CMV is a sexually transmitted disease that attacks the epithelial cells, which coat most of our body and organs; yet, it rarely causes problems in otherwise healthy individuals. If you do experience symptoms, they will likely include low-grade fever, swollen lymph nodes in the neck, poor appetite, and malaise (not feeling well). Only those with weakened immune systems (due to HIV or cancer, for example) are at risk for more serious consequences, such as pneumonia. CMV in pregnant women, however, does pose a risk to the woman and, especially, her baby.

How Common Is CMV?

About 50 to 80% of adult women in the have had CMV at some point in their lives. CMV can remain dormant for years after an initial infection; so, if you've had the virus previously and are currently experiencing symptoms, it is likely that you are experiencing a reinfection-not a new infection. While a past infection may give you some antibodies against CMV, these antibodies do not necessarily protect a fetus from infection. (Antibodies are cells produced by your immune system to fight specific infectious agents that have entered your body.)

How Is CMV Transmitted?

CMV is transmitted via close, personal contact with an infected person, usually through saliva, blood, urine, breast milk, or sexual contact. Young children often get the virus from close contact with playmates, particularly in day-care centers. Infected children can also transmit the virus to adults. Note that it may take 28 to 60 days after an initial infection before you experience any symptoms.

If I Have CMV, Will I Infect My Baby?

A mother can transmit CMV to her baby:

• before birth, through transmission of the virus across the placenta into the baby's blood;
• during birth, through contact with secretions from the mother's cervix, blood, or urine; or
• after birth, through infected breast milk.

Infections that occur during pregnancy are the most common and the most serious. Most babies who contract the virus during or after birth do not experience serious problems.

If your initial CMV infection occurred before you became pregnant and you are currently showing symptoms (recurrent infection), the risk of fetal infection is much lower than if this is your first infection. In fact, babies born to women with a recurrent infection rarely show symptoms at the time of birth-though 5 to 10% of babies later show signs of infection, most often hearing loss.

Between 1 and 4% of previously uninfected women become infected during pregnancy. In these cases, 40 to 50% of babies become infected. The risk of viral transmission is greatest when a mother becomes infected during her third trimester; however, the risk of severe injury to the baby is greatest when a mother becomes infected during her first trimester.

How Can CMV Be Prevented?

• Because CMV is a sexually transmitted disease, sexual promiscuity greatly increases your risk of infection. Latex condoms provide an effective barrier to the virus.
• Health care workers, day-care employees, elementary school teachers, and parents should help keep children's hands and toys clean.
• Only CMV-free blood products should be used in transfusions. All potential organ or semen donors should be screened for CMV infection.
• Health care workers should use caution when treating patients and handling potentially infected body fluids.

At present, there is no vaccine for CMV. Antiviral medications, such as ganciclovir and foscarnet, work reasonably well against CMV, but they do not prevent or treat fetal CMV infections.

Should Every Pregnant Woman Be Tested for CMV?

Most experts agree that testing should be limited to women who have symptoms of acute CMV infection, who have had definite exposure to CMV, or who have weakened immune systems (due to cancer, HIV, or some other infection).

How Will My Baby Be Treated If I Am Infected with CMV?

Infants delivered to infected mothers require careful evaluation at birth to detect immediate signs of injury, such as low platelet count, small head size, low birth weight, eye abnormalities, and enlarged liver and spleen. Children that appear normal still require long-term medical attention, especially to screen for visual and hearing abnormalities, as well as learning and behavioral disorders.

For more information about CMV during pregnancy, go to Diagnosis of CMV Infection in Pregnancy and Transmission of CMV to Fetus.

For information about other infections screened early in pregnancy, go to Toxoplasmosis in Pregnancy, Screening for Rubella Screening for Parvovirus in Pregnancy, Screening for HIV in Pregnancy, Varicella, Syphilis in Pregnancy, Listeria, and Hepatitis in Pregnancy.