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Having a cytomegalovirus (CMV) blood test during pregnancy can diagnose a CMV infection. But it can't always tell when the infection occurred. Also, it can't diagnose an infection in an unborn baby.


If you are worried about your risk of CMV, speak to your GP, obstetrician or midwife.

Diagnosing CMV in an unborn baby

A fetal anatomy ultrasound scan can sometimes detect signs that your baby may have congenital CMV. Particularly if it shows that your baby’s brain is not developing properly.

Fetal anatomy ultrasound scan

Treatment for cytomegalovirus (CMV) in pregnancy and babies

Amniocentesis testing for CMV in unborn babies

Amniocentesis is a test carried out during pregnancy. It is not a routine test in pregnancy. It is only carried out if the ultrasound scan suggests that your baby might have congenital CMV.

Amniocentesis checks if your baby has developed, or could develop, a serious condition. To do this, a needle is used to take a sample of amniotic fluid. This is the fluid that surrounds your developing baby in the womb.

Amniocentesis will not detect what effect CMV will have on your baby or any long-term issues.

There is a 1% risk of miscarriage with an amniocentesis test.

If you need the test, it will be provided as part of your antenatal care. You will not have to pay for it.


Diagnosing CMV in newborn babies

Pee (urine) and blood samples are used to test for CMV in newborn babies. It is not a routine test, but it will be done if there are any concerns that your baby might have CMV.

Page last reviewed: 12 February 2024
Next review due: 12 February 2027

This project has received funding from the Government of Ireland’s Sláintecare Integration Fund 2019 under Grant Agreement Number 123.