June is National CMV Awareness Month. CMV, or Cytomegalovirus, is a common virus which closely resembles a cold. 80-85% of women in the United States will test positive for CMV antibodies, meaning they contracted the virus earlier in their lives (likely as a child). If these women were to come into contact with the virus in the future, their immune systems can easily fight off the infection.
Fertility clinics will often require mothers pursuing embryo adoption to take a blood test for CMV antibodies.
About a decade ago, scientists and researchers started to find a connection between certain mild medical disabilities in children and women who contracted CMV for the first time during their pregnancy. Although, this is rare: The Centers of Disease Control states that one out of every 200 babies is born with congenital CMV, and only one out of every 5 of these babies will show symptoms or long term health problems. Most of the time, babies born with a congenital CMV infection will not have signs or symptoms.
However, fertility clinics have started testing for CMV antibodies in women who would use donor gametes (like sperm, eggs, and embryos) due to the risk.
If you test positive for CMV antibodies, you are very unlikely to contract CMV during your pregnancy. If you test negative for CMV antibodies (i.e. you have never contracted this particular virus before), it means you could be at a greater risk for contracting it during your pregnancy. As a result, you should take precautions during pregnancy to prevent a CMV infection, which includes thorough hand washing, using caution when in contact with bodily fluids, and refrain from prolonged contact with younger children.
So what happens if you test negative for CMV antibodies? Fertility doctors want their patient’s to be thoroughly educated about risks of fertility treatments. They may suggest to you that you should only match with donor gametes from individuals who have also tested negative for CMV, to reduce the risk. However, this is likely unnecessary since there have been no reported cases of a women contracting CMV from donor embryos. In reality, researchers speculate that it is highly unlikely the virus would even be present when the donors were having their eggs or sperm retrieved, and even less likely for the virus to survive the cleaning and freezing process that embryos undergo.
If you decide to wait for embryos who are labeled CMV negative, it may take more time to find the right match. Both genetic parents would need to test negative for CMV antibodies, so consequentially, 80-85% of frozen embryos are labeled CMV positive.