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Cytomegalovirus (CMV) is a common virus. It is usually harmless. It can infect almost anyone.

Once you're infected with CMV, the virus stays in your body for life. Most people won’t know they have CMV because it doesn’t usually cause any problems for healthy people.

But if you are pregnant and you get CMV, it may be a concern. This is because the infection can be passed to your baby in the womb. This is called a congenital CMV infection. A congenital infection affects unborn and newborn babies.

About 60,000 babies are born every year in Ireland. Between 150 to 450 are born with congenital CMV. Most babies born with congenital CMV won’t develop any long-term problems, but a small number will.


If you are worried about your risk of CMV, speak to your GP, obstetrician or midwife. They may recommend that you get a blood test to check for CMV.

Types of CMV

There are 3 different types of CMV infection:

  • primary CMV infection - when you are infected with CMV for the first time
  • CMV reactivation - a previous infection that becomes active again
  • CMV reinfection - when you are infected with a different strain of the virus

Congenital CMV is a primary CMV infection in an unborn or newborn baby.

Types of cytomegalovirus (CMV) in pregnancy

Treatment for CMV in pregnancy and in unborn babies

There is no recommended treatment for congenital CMV during pregnancy.

In most cases, the virus will not cause any problems for your baby.

Treatment for congenital CMV in newborn babies will depend on the type of symptoms your baby has.

Treatment for cytomegalovirus (CMV) in pregnancy and babies

Symptoms of CMV

If you are healthy and you get CMV, you may not have any symptoms.

If you do have symptoms, they will be flu-like symptoms. Symptoms usually get better on their own within 3 weeks.

If you have a weak immune system, a CMV infection can cause a wide range of symptoms.

Signs and symptoms of congenital CMV can range from mild to severe.

Read more about symptoms of congenital CMV

Causes of CMV in pregnancy and congenital CMV

CMV can be spread through body fluids, including:

  • saliva (spit)
  • poo (faeces)
  • blood
  • breast milk
  • semen
  • tears
  • pee (urine)
  • vaginal fluids

If you are breastfeeding, infecting your newborn baby with CMV is not a big concern. This is not congenital CMV and does not cause the same issues as congenital CMV. The health benefits your baby will get from breastfeeding far outweigh any potential risk from CMV.

Toddlers and preschool children are most likely to spread CMV. CMV infection in healthy children is usually not serious.

You are more at risk of catching CMV if you:

  • work with children
  • already have a young family

Diagnosing CMV

Having a CMV blood test during your 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.

There is no routine test to diagnose CMV in unborn babies.

Amniocentesis is a test carried out while you are pregnant. It is not a routine test in pregnancy. It is only carried out if your ultrasound scan indicated that your baby might have congenital CMV.

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

Diagnosing CMV during pregnancy


Preventing CMV

There are ways you can reduce your risk of catching CMV. Especially if you are pregnant or planning to get pregnant.

Ways you can reduce your risk of catching CMV:

  • Wash your hands with soap and hot water - especially before and after eating, feeding, changing a nappy and wiping your child’s nose.
  • Wash toys or other items that get young children's saliva or urine on them.
  • Do not share food, cutlery, drinking glasses, or soothers with young children.
  • Do not get saliva in your mouth when kissing a child.


Bring an alcohol-based hand sanitiser with you wherever you go. Avoid touching your eyes, nose and mouth if you have body fluids on your hands.

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.