Cytomegalovirus and pregnancy

Cytomegalovirus (also called CMV) is a kind of herpesvirus. There are many kinds of herpesviruses. Some are sexually transmitted diseases, some can cause problems like cold sores and some can cause infections like CMV. Many people get CMV at some point in their lives, most often during childhood.

If you have CMV during pregnancy, you have a 1-in-3 chance (33 percent) of passing it to your baby. CMV is the most common virus passed from mothers to babies during pregnancy. About 1 to 4 in 100 women (1 to 4 percent) have CMV during pregnancy. Most babies born with CMV don’t have health problems caused by the virus. But CMV can cause problems for some babies, including microcephaly. This is a birth defect in which a baby’s head is smaller than expected, compared to babies of the same sex and age.

You can pass CMV to your baby at any time during pregnancy. It’s more likely to cause problems for your baby if it happens in the early part of pregnancy. You also can pass CMV to your baby during labor and birth and during breastfeeding. If your baby gets the virus during these times, he’s less likely to have health problems than if he gets the virus during pregnancy.

About half of all pregnant women have had CMV in the past. If you’ve already had it, you don’t need to worry about getting it again. Once you’ve been infected, CMV stays in your body for life. You can still pass it to your baby, but this is rare and usually doesn’t cause any harm to your baby.

How do you know if you have CMV?

Most people with CMV have no signs or symptoms. But some may have:

  • A sore throat
  • A fever for a few days
  • Swollen glands
  • Fatigue (feeling tired all the time)

Tell your health care provider if you think you may have CMV. Your provider can give you a blood test to see if you have it.

If you have a weak immune system, CMV can cause serious health problems, including pneumonia or eye infections. For example, CMV can cause these kinds of problems for people with HIV.

How is CMV treated during pregnancy?

If your blood test is positive for CMV, your provider can test your baby for the virus using amniocentesis (also called amnio). During this test, your provider pushes a thin needle through your belly to remove a small amount of amniotic fluid. Amniotic fluid is the fluid that surrounds your baby in the womb. A lab tests the fluid for CMV. Your provider also may use ultrasound to check for physical signs that your baby is infected. An ultrasound uses sound waves and a computer screen to show a picture of your baby inside the womb.

Scientists are working to develop a vaccine for CMV. They’re also looking for other ways to prevent babies from being born with CMV.

How do you get infected with CMV?

You can get CMV by coming in contact with bodily fluid from a person who caries the virus. Bodily fluids include saliva, breast milk, semen, mucus, urine and blood.

Women usually get infected by having sex with someone who has CMV or by having contact with young children with CMV. As many as 7 in 10 children (70 percent) between 1 and 3 years of age who go to day care may have CMV. They can pass it on to their families, caretakers and other children.

You may be more likely than other people to get CMV if you:

  • Have young children at home
  • Work with young children, for example as a child care worker or a teacher
  • Work in health care. If you’re a health care worker in contact with people who have CMV, including newborns, use standard precautions to keep from getting infected yourself. You may want to get tested before pregnancy to see if you’ve had CMV.

How can you protect yourself from CMV?

Here are some things you can do:

  • If you’re around children, wash your hands well after being in contact with their body fluids. For example, wash your hands after changing diapers, wiping noses and picking up toys.
  • Carefully throw away used diapers and tissues.
  • Don’t kiss young children on the mouth or cheek.
  • Don’t share food, glasses, cups, forks or other utensils with young children or with anyone who may have CMV.
  • If your partner has CMV, use a latex condom during sex.

More information

Last reviewed: November, 2013