Cytomegalovirus (CMV) is a virus that can be transmitted to a developing fetus before birth. CMV is a member of the herpes family of viruses that also includes chickenpox and mono. Primary CMV infection occurs in people who have never been exposed to the CMV virus before. Once a person becomes infected with CMV, the virus remains alive but dormant inside that person's body for the rest of their lives. Recurrent CMV infection, is when a dormant virus become active again. This can occur if a person's immune system becomes weakened such as in the elderly or in people who AIDs. CMV infection is usually harmless and rarely causes illness. However, for pregnant women, primary CMV infection can cause more serious problems than recurrent CMV infection. 

Most women who are infected with CMV whether pregnant or not, will not develop any symptoms of the infection. Those that do experience symptoms may see fever, swollen glands or lethargy (feeling tired or rundown) 

 

About 50 to 85% of the adults in the United States will become infected with CMV by the time they turn 40.  About half of expectant mothers have never been infected with CMV. About 1% to 4% of uninfected mothers have primary CMV infection during their pregnancy. If a pregnant woman has never been exposed to CMV and has her first infection during pregnancy, there is a chance that the fetus could become infected before the mother's body can eliminate the virus. About one third of women who become infected with CMV for the first time during pregnancy pass the virus to their unborn babies.  Thus, CMV is the most common cause of congenital viral infection in the United States.

 

On average, about 40% of the babies born to mothers who had a primary CMV infection during pregnancy will become infected themselves. Of the 40% of babies who become infected, twenty percent of babies born with an infection develop medical complications over the first few years of life. Those symptoms can include low birth weight, deafness, blindness, mental retardation, small head, seizures, jaundice, brittle teeth and damage to the liver and spleen. While a child may develop some of the above symptoms, no baby develops all the symptoms and some infants have no symptoms at all. Each year in the United States, about 1 in 750 children are born with or develop disabilities as a result of CMV infection.

 

For women who have been infected at least 6 months prior to conception, the rate of newborn CMV infection is about 1%, and these infants appear to have no significant illness or abnormalities. 

CMV antibody testing

Most CMV infections are rarely diagnosed because the virus usually produces few, if any, symptoms. However, people who have had CMV develop antibodies to the virus which remain in their body for the rest of their life.  Two types of CMV antibodies may be found in the blood: IgM and IgG.

If both CMV IgG and IgM are present in a symptomatic patient, then it is likely that he or she has either recently been exposed to CMV for the first time or that a previous CMV infection has been reactivated. This can be confirmed by measuring IgG levels again 2 or 3 weeks later. A high level of IgG is not as important as a rising level. If there is a 4-fold increase in IgG between the first and second sample, then the patient has an active CMV infection (primary or reactivated). 

CMV and Donor IUI 

The FDA requires that CMV testing be performed on all men who intend to donate sperm. A positive result however, doesn't necessarily mean that a man will be ineligible to donate.  Sperm banks will obtain semen samples from potential donors and then quarantine those specimens for at least six months. During that time, the man may have CMV antibody levels tested several times. If the antibody tests indicate the possibility of a CMV infection close to the time of the sperm donation, the man will not be allowed to donate those specimens. If the testing is uncertain, those men will also now be allowed to use those specimens. However, if a man tests positive for CMV IgG only, indicating a past infection, he will be allowed to donate. Those samples will be labeled in the sperm bank database as CMV positive. 

 

Women who are considering attempting pregnancy with donor sperm should have CMV antibody testing. Those women who have had a past infection are at very low risk of transmitting CMV infection to as fetus. They are at little to no risk from using a CMV positive donor. women who have never been exposed to CMV however, should consider using a CMV negative sperm donor. Although the risk from CMV positive donors may be small, it is impossible to determine with certainty whether there might be some risk for infection. Therefore for the CMV negative woman, these specimens are best avoided.