Cytomegalovirus (also called CMV) is the most common infection passed from pregnant people to babies during pregnancy.
More than half of adults have been infected with CMV by age 40 but most don’t know they’ve been infected.
Once you’re infected with CMV, it stays in your body for the rest of your life.
If you get infected with CMV during pregnancy, it may cause pregnancy loss or serious health problems in your baby, including preterm birth or low birthweight, or hearing loss at birth or later in life.
CMV is the leading cause of hearing loss in this country, causing 1 in 3 cases of hearing loss.
What is cytomegalovirus?
Cytomegalovirus (also called CMV) is a common virus that infects people of all ages. More than half of adults in the United States become infected with CMV by age 40. Once CMV is in your body, you have it for the rest of your life. The virus can reactivate and cause another infection. You can also be re-infected with a different strain (variety) of the virus.
Most people with CMV infection have no symptoms and aren’t aware that they have been infected. CMV infection usually isn’t harmful in healthy adults or children because their immune system protects their bodies from infection. But CMV can cause serious health problems for some, including:
- Babies who get infected before birth
- Preterm babies (babies born before 37 weeks of pregnancy) or low birthweight babies (babies born weighing less than 5 pounds, 8 ounces)
- People with weakened immune systems. People with weak immune systems include people living with a serious illness, like HIV, people getting treatment for cancer and people who’ve had a bone marrow or organ transplant.
CMV is the most common infection passed from pregnant people to babies during pregnancy. One in 3 pregnant people passes the infection on to their babies. If you have CMV during pregnancy, the virus in your blood can pass through the placenta to your baby. The placenta supplies the baby with food and oxygen through the umbilical cord. It’s possible for CMV to cause the death of a baby during pregnancy (pregnancy loss).
When a baby gets CMV during pregnancy, it’s called congenital CMV. Congenital means that it’s present at birth. One in 200 babies in the U.S. is born with CMV. Most babies with congenital CMV don’t have problems, but some get sick or have long-term health problems. A baby also may get infected after birth if they come in contact with infected body fluids.
There’s no cure for CMV, but medicines can help treat CMV in newborns and people with weak immune systems.
CMV is part of the family of herpes viruses. It’s related to the viruses that cause chickenpox, herpes simplex (also called HSV) and mononucleosis (also called mono). Once you’re infected with CMV, it stays in your body for life. If you’re healthy, CMV usually stays inactive but it can become active again, especially if you get a disease or take medicine that weakens your immune system. You also can get infected again with a different strain of the virus.
What are the signs and symptoms of CMV?
Most people with CMV don’t know they have the infection because they don’t have signs or symptoms. Signs and symptoms of CMV can be different in healthy people, babies and people with weak immune systems.
Signs and symptoms of CMV in healthy people may include:
- Chills and/or sweats
- Decreased appetite
- Fatigue (being very tired and having little energy)
- Muscle aches
- Sore throat
- Swollen glands
CMV sometimes can cause hepatitis and mononucleosis (mono). Hepatitis is a disease caused by a virus that attacks the liver. Mono is a disease that can cause extreme fatigue, head and body aches, sore throat, swollen lymph nodes and swollen spleen or liver.
People with weakened immune systems who get CMV can have more serious problems that can affect the eyes, lungs, liver, esophagus, stomach and intestines. The esophagus is the tube that connects the mouth and stomach. The intestines are long tubes that help your body break down (digest) food.
People who are more likely to have the signs and symptoms of CMV include:
- Babies who became infected with CMV before they are born (congenital CMV).
- Babies who become infected during birth or shortly after (perinatal CMV). This group includes babies infected while nursing.
- People who have weakened immune systems, such as those who have had an organ, bone marrow or stem cell transplant, or those who are infected with HIV.
Contact your health care provider if you have the symptoms of mono while pregnant. These include:
- Extreme fatigue
- Head and body aches
- Sore throat
- Swollen lymph nodes
- Swollen spleen or liver.
How does CMV spread?
You get CMV by coming in direct contact with body fluids from a person who’s infected with CMV. Body fluids that can contain CMV include:
- Breast milk
- Vaginal fluids
CMV spreads in several ways:
- Passing it to your baby during pregnancy, labor, birth, or nursing
- Touching your eyes or the inside of your mouth or nose after direct contact with an infected person’s body fluids, including saliva, urine, blood, tears, semen and human milk.
- Having sexual contact or kissing an infected person
- Getting an organ, bone marrow or stem cell transplant or blood transfusion
Adults usually get CMV by having sex with someone who has CMV or by having contact with young children who have CMV.
You may be more likely than other people to get CMV if you:
- Have young children. CMV often spreads during diaper changes, bathing and other close contact with babies and young children. Children can get infected with CMV at child care or school and pass it on to their families, caregivers and other children.
- Work with young children. For example, you’re a child care worker or a teacher. CMV spreads easily in child care centers or preschools where children share toys that may carry CMV.
- Have sex with someone who has CMV.
- Work in a health care setting, like a health care provider’s office or a laboratory, where you may have contact with infected body fluids
- Have a blood transfusion or organ transplant. A blood transfusion is when you have new blood put into your body. An organ transplant is when you have a new organ, like a heart or kidney, put into your body.
Can I give CMV to my baby?
You’re more likely to pass CMV to your baby if you get infected during pregnancy than if you had an infection before you got pregnant. If you have a CMV infection during pregnancy, you have a 1-in-3 chance (33 percent) of passing it to your baby. If you were infected with CMV before you got pregnant, the chance of passing it to your baby drops to about 1 in 100.
More than half of adults have had a CMV infection by the time they are 40 years old, and about 1 to 4 in 100 people (1 to 4 percent) get infected with CMV for the first time during pregnancy.
You can pass CMV to your baby at any time during pregnancy. But you are more likely to pass it on if you get infected for the first time during pregnancy or if a past CMV infection becomes active again, especially in the third trimester. You also can pass CMV to your baby during labor and birth, or while nursing. If your baby gets the virus during these times and was born at a healthy weight, they probably won’t have health problems. Preterm babies (babies born before 37 weeks of pregnancy) and low-birthweight babies (babies born weighing less than 5 pounds, 8 ounces) may get sick if they’re infected during birth or while you’re nursing.
If you had a CMV infection before you got pregnant, you can still pass it to your baby, but this is rare.
How does CMV affect babies?
Most babies born with CMV never show signs of the disease and don’t have health problems.
However, babies who are infected with CMV at birth may have long-term health problems, including:
- Hearing loss
- Intellectual and developmental disabilities. These are problems with how the brain works that can cause a person to have trouble or delays in physical development, learning, communicating, taking care of themselves or getting along with others.
- Coordination issues or muscle weakness
- Smaller than expected head (called microcephaly)
- Seizures or convulsions
- Vision loss
Some babies with congenital CMV who don’t show the signs of the disease at birth may still have or develop hearing loss. It may affect one ear or both ears. Sometimes hearing loss can get worse as a baby grows up.
How is CMV diagnosed during pregnancy?
You typically won’t be tested for CMV during prenatal testing. Tell your health care provider if you think you may have CMV or you think you may have been exposed to CMV. Your provider can give you a blood test or test other body fluids to see if you’re infected. Blood tests can help you know whether you have a new infection or if you had a past infection.
Can a baby get tested for CMV before birth?
Yes. If a blood test shows you have a new CMV infection during pregnancy, your provider may recommend testing your baby for the virus using amniocentesis (also called amnio). An amniocentesis is a test that takes some amniotic fluid from around your baby before they are born to check for birth defects and genetic conditions in your baby. You can get this test at 15 to 20 weeks of pregnancy. Your provider also may use ultrasound to check for physical signs that your baby has CMV. An ultrasound (also called sonogram) uses sound waves to show a picture of your baby before they are born. If your provider thinks that your baby may have CMV, your baby’s urine and saliva may be tested to check for the virus.
How is CMV treated during pregnancy?
There is no cure for CMV, but medications can control infections. Most healthy adults with CMV don’t need treatment. This includes during pregnancy.
People with weakened immune systems may need treatment with an antiviral medicine. These medicines kill infections caused by viruses. Medicines used to treat CMV include ganciclovir, valganciclovir, cidofovir and foscarnet.
How are babies diagnosed with CMV after birth?
About 1 in 200 babies (less than 1 percent) is born with congenital CMV in this country each year. Your baby’s provider can diagnose CMV infection by testing your newborn baby’s saliva, urine or blood. Testing should be done within 2 to 3 weeks after your baby is born to confirm that your baby has congenital CMV.
Most babies with congenital CMV don’t have health problems, but about 1 in 5 babies with congenital CMV can get sick from the virus or have long-term health problems.
Some babies born with CMV have signs and symptoms, including:
- Hearing loss. This is the most common health problem in babies born with CMV. A baby may have hearing loss at birth or it may develop later in childhood.
- Eye damage
- Problems with the spleen, liver or lungs. The spleen is an organ that filters blood in your body and fights infection.
- Jaundice. Jaundice is when a baby’s eyes and skin look yellow. A baby has jaundice when their liver isn’t fully developed or isn’t working well.
- Low birthweight (less than 5 pounds, 8 ounces)
- Smaller than expected head (called microcephaly)
- Neurologic problems, including seizures or convulsions
- Preterm birth
- Skin rash or purple splotches on the skin
- Swollen lymph nodes
How is CMV treated after birth?
Babies who show the signs of CMV at birth may be treated with antiviral medications. Antiviral medication may lower your baby’s risk of developing health problems and hearing loss. These medications can include ganciclovir or valganciclovir. However, both can cause serious side effects. More research about using antiviral medications on babies is needed.
Using antivirals to treat babies with congenital CMV who have no signs at birth is not currently recommended.
Babies with congenital CMV, with or without signs at birth, should have regular hearing checks. If your baby has a hearing issue, the earlier it’s detected, the more your baby can benefit from treatment. You should also follow up regularly with your baby’s doctor to discuss any care or additional services that your baby may need. This may include speech services or occupational therapy.
Can I nurse my baby if I have CMV?
CMV can be transmitted to your baby through breast milk while nursing. If you have CMV, you can nurse your baby if they were full term at birth. However, if your baby was born before 30 weeks of pregnancy and weighs less than 3.3 pounds (1,500 grams), talk to your provider before nursing. Some preterm and low birthweight babies can get sick from infected breast milk. Freezing and pasteurizing (heating) breast milk can decrease the risk of transmission. However, freezing does not make nursing completely safe for your baby
How can you protect yourself from CMV?
Here are some things you can do:
- Wash your hands often with soap and water, especially after being in contact with body fluids from babies or children. Carefully throw away used diapers and tissues. Wash your hands after changing diapers, feeding a child, wiping noses and picking up toys.
- Avoid contact with tears or saliva if you kiss a child, especially if you’re pregnant. Kiss babies and children on the cheek or head instead of on the lips.
- Don’t share toothbrushes, food, drinks, cups, straws, forks or other utensils with young children or with anyone who may have CMV. Don’t put a baby’s pacifier in your mouth.
- Clean toys and countertops often.
- If your partner has CMV, use a latex condom during sex..
- If you’re a health care worker in contact with people who have CMV, including newborns, follow workplace safety rules to protect yourself from infection. Wash your hands often and wear gloves.
Scientists are working to develop vaccines for CMV. Vaccines make you immune to certain diseases. These vaccines may help prevent CMV infection in pregnant people and babies, and they may help reduce the chance that a baby born to an infected person will have health problems.
For more information
Last reviewed: August 2021