Cytomegalovirus (CMV) and pregnancy

Cytomegalovirus (or CMV for short) is a common virus that affects people of all ages around the globe. It usually isn’t harmful to healthy adults or children but can be dangerous to a baby, which is why it’s helpful to learn about CMV before you get pregnant. 
Once you get infected with CMV, the virus remains inside your body for the rest of your life. It stays mostly inactive when you are healthy, but it can be activated by another disease or medication that weakens your immune system. It’s also possible to get infected again with another variant of the virus. Over 50% of adults have already been infected with CMV by the time they reach age 40.

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Impact of cytomegalovirus on pregnancy

CMV is the most common infection passed between a pregnant mother and her baby. If you were infected with CMV before getting pregnant, there is about a 1% chance of passing it to your baby. Women who get infected with CMV during pregnancy have around a 33% chance of passing it to the baby. 

CMV can cause problems for a pregnancy and a baby, including pregnancy loss. If a baby becomes infected with CMV while still in the womb (congenital CMV), they may have a premature birth, low birth weight, and other health problems that are apparent at birth, including yellow skin and eyes (jaundice), enlarged liver or spleen, rash, abnormally small head, seizures, and pneumonia. 

Some babies with congenital CMV look healthy at birth but may develop long-term health problems later on (months or years later). These can include hearing loss, vision loss, seizures, and intellectual disabilities. But the good news is that most babies born with CMV don’t have health problems – only 1 in 5 babies with congenital CMV experience issues.

How cytomegalovirus spreads

CMV spreads through direct contact with the bodily fluids of an infected person, such as during sex or when changing a baby’s diaper. Pregnant women who become infected with CMV can pass it along to their babies through the placenta or during labor or birth. It can also spread via breastfeeding. 

Symptoms of cytomegalovirus

Most people who become infected with CMV experience no symptoms and don’t know that they have CMV. Signs of CMV differ between healthy adults, babies, and those with weakened immune systems. 

For healthy adults, the symptoms of CMV include:

• Fever
• Fatigue
• Sore throat
• Muscle aches
• Chills or sweats
• Decreased appetite 
• Swollen glands

Sometimes, CMV can lead to mononucleosis (also called mono) or hepatitis (inflammation of the liver). 

CMV infection can be serious or fatal for people with a weakened immune system, particularly those who have gotten an organ, stem cell, or bone marrow transplant.

Diagnosis of cytomegalovirus

Healthcare providers diagnose CMV with a blood test. This test can tell you if you have a new infection or were infected with CMV in the past.

If blood test results reveal a new CMV infection during your pregnancy, your doctor may recommend tests for your baby to see if they have been infected as well. You may be offered amniocentesis, a test that checks for birth defects and genetic conditions by taking a sample of amniotic fluid surrounding your baby. This test carries a small risk of complications, including miscarriage and uterine infection. An ultrasound can look for physical signs of CMV in your baby. After birth, your doctor can test your baby’s saliva, urine, or blood for CMV. 

Treatment of cytomegalovirus

Researchers are working on developing a vaccine for CMV, but there’s no vaccine currently available. To protect yourself from becoming infected with CMV during pregnancy, here are some tips you can follow:

• Wash your hands frequently, particularly after coming into contact with bodily fluids from babies or children (including tears, saliva, urine, and poo)
• Wear a condom during sex if your partner has CMV
• Clean any toys and countertops often

Most healthy adults don’t need treatment after becoming infected with CMV, including during pregnancy. People with weakened immune systems may need to be treated using an antiviral medication to help them clear the infection. 

Babies who exhibit symptoms of CMV at birth might also be treated using antiviral medicine, which can reduce the chance of developing health problems and hearing loss. It’s not recommended to treat babies with antiviral medication who don’t have symptoms of CMV. Babies who test positive for congenital CMV should also have regular hearing checkups and additional health screenings to catch any problems early and begin treatment.

• Cytomegalovirus (CMV) infection. Mayo Clinic. Accessed 10 January 2023. 
• Cytomegalovirus and pregnancy. March of Dimes. Accessed 10 January 2023. 
• Amniocentesis. March of Dimes. Accessed 11 January 2023. 
• About Cytomegalovirus (CMV). Centers for Disease Control and Prevention. Accessed 11 January 2023.