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Cytomegalovirus (CMV) can be spread through body fluids, including:

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

Your chance of getting CMV from casual contact is very low. For example, shaking hands, speaking with someone or on public transport.

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.

Diagnosing cytomegalovirus (CMV) in pregnancy

When you are more at risk of catching CMV

You are more at risk of catching CMV if you:

  • work with children
  • already have a young family

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

Wash your hands regularly if you:

  • are pregnant or trying for a baby
  • have a weakened immune system

Particularly before and after:

  • eating
  • changing a nappy
  • feeding your child
  • tidying away toys

Bring an alcohol-based hand sanitiser with you wherever you go.


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

Preventing cytomegalovirus (CMV) in pregnancy

When CMV can be spread

CMV can only be spread when it is active. This means that the virus is replicating inside you and it can be shed in your saliva & urine.

It is active when:

  • you catch the virus for the first time
  • the virus has re-activated
  • you have been reinfected with a different strain (type) of the virus

Most people won’t know they have CMV because it doesn’t usually cause any problems for healthy people.

How long the virus is active

After an adult is first infected, the virus may be active for a period of weeks to months.

The virus may be active for a period of months to years for a baby with:

  • a congenital infection
  • an infection in the first years of life

Chances of your unborn baby developing CMV

The chance of developing a primary CMV infection during pregnancy and your baby being infected is low. If you do develop a primary CMV infection during your pregnancy, there is a 4 in 10 chance your baby will be infected.

You may have a reinfection or reactivated CMV infection during your pregnancy. If so, there is a low chance (1 in 100) of your baby being infected.

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.