Cytomegalovirus (CMV) during pregnancy

What is CMV?

Cytomegalovirus (CMV) is a virus that is especially common in adolescents and children under 2 years of age. It often doesn’t cause any obvious symptoms, so you may not know you’ve been infected. About 1 in 2 people have had CMV by the time they become adults.

After you first become infected, CMV stays in your body and becomes inactive. It can become active again at times when your immune system is weaker than usual, such as when you’re pregnant.

It’s possible for an unborn baby to become infected with CMV. This can sometimes cause serious problems.

How does CMV spread?

CMV is transmitted from person to person through contact with body fluids, such as saliva, nasal mucus, urine, vaginal discharge, semen and breast milk. It can be spread by coughing and sneezing and by contact with objects that have body fluids on them. It’s also possible to get CMV from having sex, a blood transfusion or an organ transplant. Babies can become infected with CMV during breastfeeding.

If a child has had CMV, the virus can continue to appear in their urine and saliva for years afterwards and can infect other people who haven’t had CMV. Some people get CMV while they’re pregnant. This can happen through contact with toys, tissues or nappies used by children who have had CMV. People with young children at home and people who work in childcare centres are at higher risk of catching CMV if they haven’t had it before.

How do I know if I have CMV?

CMV usually doesn't cause any noticeable symptoms. However, in some people, it can cause mild symptoms such as fever, swollen glands, tiredness, sore throat and a cough. Sometimes it can cause mild liver inflammation. These symptoms usually go away by themselves.

CMV can cause serious illness in people with a weak immune system, for example people with HIV or who are having chemotherapy for cancer.

Most people don’t know they have CMV infection, or if they have had it before. You might find out from a blood test that you’ve had it.

Could I give CMV to my baby?

If you have CMV when you’re pregnant, the virus can travel across the placenta and infect your baby. This is called congenital CMV.

This can happen if:

• it’s the first time you’ve been infected with CMV (this is called primary infection)
• you’ve had CMV before and the virus in your body becomes active again (this is called reactivation)
• you get infected with a different strain of CMV than you’ve had before

You are more likely to pass the virus on to your baby if you have a primary CMV infection during pregnancy. CMV can spread to your baby at any stage of pregnancy, but risk is higher in the first half of pregnancy.

How does CMV affect unborn babies?

Most babies born with CMV don’t have symptoms or health problems as a result of the virus, but some do. Your baby is more likely to be affected if it’s the first time you’ve been infected with CMV. Your doctor might see signs of congenital CMV on a pregnancy ultrasound.

About 3 in 10 people who get CMV for the first time in pregnancy will pass it on to their baby. About 1 in 10 of these babies will be born with symptoms. In total, about 1 or 2 out of every 10 babies infected with CMV during pregnancy will have a long-term health problem.

If your baby is born with symptoms of congenital CMV, these may include:

• rash
• small head size
• enlarged liver and spleen
• pneumonia
• low platelet count

Congenital CMV also increases your baby’s risk of poor growth, miscarriage, stillbirth and death before 3 months of age.

If your baby is born without symptoms, there’s a chance they could develop health problems later. These may include:

• poor hearing – this is the most common problem
• poor vision
• intellectual impairment
• developmental delay
• cerebral palsy
• seizures

Babies who are born without any symptoms or hearing loss have a lower chance of problems.

Should I be tested for CMV?

There is a blood test for CMV, but in Australia it’s not routinely done in pregnancy. CMV testing in pregnancy is recommended for:

• people who develop symptoms of a viral infection suggestive of CMV
• people who come into frequent contact with young children (such as child care workers)
• people who know they have been exposed to someone with a new CMV infection
• people who have had a pregnancy ultrasound that shows signs of congenital CMV

You can check with your doctor if you need to test for CMV. If you have a test that shows that you have CMV, you may need further testing to see if your baby has CMV. It’s important to remember that even if your baby tests positive for CMV, this doesn’t always mean they will have health problems.

If you have CMV during pregnancy, your baby will need to be tested for CMV after birth. Babies who have an abnormal hearing test after birth may also be tested for CMV.

You can talk to your doctor about CMV testing if you have concerns.

If I get CMV during pregnancy, can my baby be treated?

Some treatments have been tried, but currently there’s no treatment that clearly lowers the risk of your baby getting CMV from you. It’s best to discuss this with your doctor.

Your baby will need to have hearing tests and eye checks for a few years to see if any problems develop.

Can I prevent getting CMV?

The best way to try to avoid infection with CMV is by practising good hygiene.

If you are pregnant, it is a good idea to:

• regularly and thoroughly wash your hands with soap and water, particularly when feeding and caring for children, changing nappies, wiping noses or handling anything with body fluids on it
• regularly clean surfaces and objects that may have body fluids on them
• wear gloves when changing nappies
• avoid contact with children’s saliva and don’t kiss them on the lips
• avoid sharing food, cups, utensils, or toothbrushes

There is no vaccine to prevent CMV infection.

If you have any concerns, you can discuss them with your doctor or midwife.