What is CMV?
Many people – probably about 60% of us - have been infected with Cytomegalovirus (CMV) without even knowing it. It is a very common virus that may have no symptoms at all or may have symptoms a bit like a common cold. The only way to know if you have had it is by doing a blood test looking for antibodies to CMV - there is no immunisation available.
How do people get CMV?
It is passed from one person to another via body fluids such as saliva, blood, semen, tears, urine, mucus, breast milk or blood transfusion.
Why is it important in pregnancy?
If a pregnant person is infected with CMV, it is not possible to predict whether a baby will become infected or how it may affect them. In the event that an unborn baby is affected, it may have long-term health problems such as deafness, seizures or developmental delay. About 1 in every 200 babies is born with congenital CMV. About 1 in 5 of those will have birth defects or other long-term issues.[1]
How are sperm donors tested for CMV?
They are tested for CMV antibodies in their blood prior to donating sperm and again at least three months after donating sperm. They are tested for two types of antibodies: IgM and IgG. IgM antibodies indicate acute or active infection with CMV and this is when the risk of passing on infection is the highest, so their samples would not be used. IgG antibodies indicate past infection.
There is a theoretical risk that a CMV positive donor could pass CMV infection via their semen samples to a recipient using those samples. Preventing the use of sperm from donors with active infection (CMV IgM positive); washing the samples for IUI and IVF; and freezing the samples further decreases the risk.
Should a CMV negative recipient use a CMV positive donor?
If someone has not been exposed to CMV in the past, (determined by blood testing), and they are concerned, they can choose a CMV negative donor. However, the risk of contracting CMV in pregnancy is greater from exposure to other people around them than it is from the use of sperm from a CMV positive donor.
Avoiding CMV
The best prevention of infection or re-infection of CMV is by avoiding contact with bodily fluids and ensuring that you wash thoroughly after, eg changing nappies. The saliva and urine of small children with CMV have high amounts of the virus.[2] Taking precautions such as washing hands thoroughly after contact with any bodily fluids and avoiding contact with saliva and urine from small children will reduce the risk.
If you have any concerns you can discuss these with the Fertility Associates team.
[2] Ibid.
