What Is CMV And How Can It Affect My Pregnancy?

Cytomegalovirus, or CMV, is a member of the herpes virus family that includes cold sores, chicken pox, and infectious mononucleosis. It’s a common virus that affects 50 to 85% percent of American adults. There is currently no vaccine for CMV.

Most people who carry the virus never experience any symptoms, and may not even know they carry it. Those that do show symptoms of an active CMV infection usually experience mild discomfort normally associated with the common cold or the flu, and show no lasting effects once they recover. During an active infection, the virus is passed through body fluids. This means it can be contracted through exposure to urine, saliva, blood, tears, breast milk, and semen.

Once a person becomes infected and passes the initial illness, the virus lies dormant in their body for the rest of their life, with little risk of recurrent infection or reactivation. Couples in which one partner contracts the virus will typically pass it on to the other through kissing and intimate contact, which results in both partners sharing the same CMV status and mutual, natural immunity. However, it is impossible to be certain of your CMV status without a blood test.

But since CMV causes more birth defects and congenital disabilities than many other well-known diseases, including spina bifida, Down syndrome, and pediatric HIV infection, it is important to understand the risks and realities of CMV.

If a woman has never encountered CMV and has her first exposure during pregnancy, there is a 30 to 40% chance of her fetus being infected as well. The majority of children born who experience a CMV infection before birth are healthy and normal. However, 10 to 15% may have complications such as hearing loss, neurological abnormalities, or decreased motor skills. Infants who are infected with CMV after they are born rarely experience any long-term complications.

How does this affect my choice of sperm donor?

Since so many people carry the CMV virus it can be difficult to find donors with a negative CMV status. To reduce the risk of adverse pregnancy outcomes, any woman planning to use donor sperm to conceive should have her CMV status tested. If the donor sperm recipient has never been exposed to CMV, her status should be negative. This means she does not have the antibodies and resistance to the virus. In order to reduce the risk of infection to her unborn child, she may want to select a sperm donor whose CMV status is also negative. If the recipient’s test results come back positive, meaning she has experienced prior exposure and subsequent immunity, she can select a sperm donor who is either positive or negative.

This may sound troubling to women using a sperm donor to conceive, but it’s important to point out that while the risk of contracting the virus from a CMV-positive donor is not absolute zero, it is extremely low. The chance of transmitting congenital CMV to a developing fetus is also extremely low. That’s why CMV-positive donors are declared acceptable.

How are sperm donors tested for CMV?

Donors are given an initial CMV screening to determine their CMV status. Donors are tested specifically for IgG and IgM antibodies. If a donor is IgG positive and IgM negative, the donor has had a past exposure to CMV but does not have an active infection. If a donor is IgG negative and IgM negative, then he has not had a CMV infection. If a donor is IgG positive and IgM positive, then he has an active infection.

All donors with an active infection are barred from donating until the donor tests IgM negative. Any potentially affected vials are discarded. Donors are then tested for CMV every 3-6 months as long as they remain a donor.

Again, the risks of using even a CMV-positive donor are very low as long as they don’t have an active infection – which is precisely what we screen for so carefully. But it’s an important issue worth discussing with your doctor or someone at our clinic, so please contact us if you have any questions or concerns.