CMV – What is it and how can it affect me and my baby?
You have probably come across the term CMV status (to be CMV positive or CMV negative). Especially if you are pregnant or looking to use donor sperm for fertility treatment. But what does CMV mean and is it something that you should be concerned about?
Here you can learn about CMV, how it may affect you and your baby and know if you should use a sperm donor with a positive or negative CMV status.
What is CMV?
Cytomegalovirus (CMV) is related to the herpes virus and is a common virus that can affect anyone. You can get infected through body fluids such as saliva, blood, urine, sperm and breast milk. Most people will get infected with the virus during childhood or early adulthood. The majority are without any symptoms but a few may develop fever, sore throat and headache. Once infected, the virus lies dormant in the body forever, with a little risk of getting reactivated. This is known as a recurrent CMV infection.
What is CMV status and what does it mean to be CMV positive?
The first time you get infected with CMV you create antibodies called CMV IgM and CMV IgG. IgM antibodies are present during an acute infection, IgG antibodies stay forever.
When no IgM antibodies nor IgG antibodies are present a person is CMV negative. This means that he/she has never been infected by CMV.
When no IgM antibodies are present, but IgG antibodies are present, a person is CMV positive. This means that he/she has had a CMV infection in the past but does not have an acute infection.
When IgM and IgG antibodies are present, there is an acute infection. If a sperm donor has an acute infection with CMV, he/she cannot donate in that period.
CMV status - screening of sperm donors
At Cryos, we perform sperm donor screening on alle the candidates for a wide variety of viruses and genetic disorders. We also screen our donors for their CMV status to accommodate use in some countries. We accept only donors who have tested IgM negative. This means that the donors do not have an active CMV infection. We accept both donors with positive and negative IgG as long as it is combined with a negative IgM (no current infection). The donors with a negative CMV status in the Sperm Donor Search have never had a CMV infection. Donors with a positive CMV status in the donor Search have previously had a CMV infection and have antibodies.
Some doctors say that sperm donors who are tested IgG positive (which means they have previously had the infection) may only be used for women who themselves are IgG positive. This means that if you know that you have previously been infected with CMV, you can use a sperm donor with a positive CMV status.
Not all countries require CMV screening. Therefore, the donors who have no CMV status shown in the Donor Search have not and will not be screened for CMV.
What is the risk of transmitting the infection to my baby?
It depends on when you became infected the first time.
Approximately 50% of all women already have antibodies to CMV before they get pregnant because they have already been infected. You can risk a reactivation of the infection during pregnancy, but the risk of passing the virus to your baby during a recurrent infection is low (about 1-2 %). So, if you got your first CMV infection before your pregnancy, the risk of passing on the virus to your baby is very small.
If you are infected with CMV for the very first time during pregnancy, the chance of passing on the virus to your baby is higher.
Will my baby be affected by an acute CMV infection?
Most babies with a CMV infection never show signs or have any health problems. Some babies infected with the virus during pregnancy may, however, have health problems that are apparent at birth or develop later during infancy or childhood.
If you want to know more about CMV, we recommend that you speak with your doctor or clinic for advice.