Cytomegalovirus (CMV) is a common virus that is usually harmless. Sometimes it causes problems in babies if you get it during pregnancy (congenital CMV).

What is cytomegalovirus (CMV)?

CMV is related to the herpes virus that causes cold sores and chickenpox.

Once you have the virus, it stays in your body for the rest of your life.

Your immune system usually controls the virus and most people do not realise they have it.

But CMV can cause serious health problems in some babies who get the virus before birth, and in people who have a weakened immune system.

Symptoms of cytomegalovirus (CMV)

CMV does not usually cause symptoms.

Some people get flu-like symptoms the first time they get CMV, including:

• a high temperature
• aching muscles
• tiredness
• skin rash
• feeling sick
• sore throat
• swollen glands

If you do have symptoms, they usually get better without treatment within about 3 weeks.

How cytomegalovirus (CMV) is spread

CMV is mainly spread through close contact with someone who already has CMV.

It can be passed on through sexual contact and contact with other body fluids including saliva, blood, breast milk, tears, pee and poo.

CMV can only be passed on when it’s “active”. The virus is active when:

• you get CMV for the first time – young children often get CMV for the first time at nursery
• the virus has “re-activated” – because you have a weakened immune system
• you’ve been re-infected – with a different type (strain) of CMV

Pregnant women can pass an “active” CMV infection on to their unborn baby. This is known as congenital CMV.

How cytomegalovirus (CMV) is treated

If CMV is not causing symptoms, you or your baby may not need any treatment.

There’s currently no treatment for CMV in pregnancy, but in most cases the virus does not cause any problems for your baby.

Antiviral medicine may be used to treat:

• babies diagnosed with congenital CMV after they’re born
• people with a weakened immune system
• people who have had a stem cell transplant or an organ transplant

Treatment weakens the virus and reduces the chance of serious problems, but it does not cure the CMV infection.

Babies born with congenital CMV may have tests to check their kidneys, liver, brain, eyes and hearing, and regular follow-up appointments until they’re around age 5.

How to reduce the chance of getting cytomegalovirus (CMV) in pregnancy

The best way to reduce the chance of getting CMV during pregnancy is to:

• wash your hands using soap and water – especially after changing nappies, feeding young children or wiping their nose
• regularly wash toys or other items that may have young children’s saliva or urine on them
• avoid sharing food, cutlery and drinking glasses or putting a child’s dummy in your mouth
• avoid kissing young children on their mouth

What is Congenital CMV?

Congenital cytomegalovirus (congenital CMV) is a group of symptoms that may occur when an infant is infected with the cytomegalovirus before birth. It occurs occurs when a mother is infected with cytomegalovirus during pregnancy and passes the infection to the fetus through the placenta.

Most infants who are infected with the virus never develop symptoms of the condition. However, approximately 10% of babies will experience health problems and/or disabilities such as poor growth in the womb, problems with the lungs, liver and/or spleen at birth; hearing loss; vision loss; intellectual disability; seizures; small head size; and/or lack of coordination.

How is Congenital CMV diagnosed and treated in pregnancy?

If a pregnant woman develops symptoms of CMV, she will be offered a blood test to see if she has developed a primary infection during pregnancy. If the blood test shows she has a new infection, she will be referred to fetal medicine doctors who specialise in caring for pregnant women with possible CMV infection. The doctor will perform an ultrasound scan and maybe offer other tests such as amniocentesis and MRI to work out if the fetus has been infected. The risk of fetal infection and the risk of the fetus being affected or harmed by CMV differs according to the gestation at which the woman became infected. The fetal medicine specialist will talk to the woman about different management options which may include antenatal therapy

More information

CMV Action are a UK based charity providing information and support for families affected by CMV

The RCOG has developed a scientific impact paper on CMV in pregnancy