In the past year, pregnant women in the United States began worrying about the spread of Zika virus in the United States and its potential to cause birth defects in their babies. But there is another viral infection already common in the United States that can also cause birth defects: cytomegalovirus, also called CMV. Even though CMV is a common virus, there are ways to protect yourself and your baby.
CMV is nearly everywhere and most people catch it early in life, which makes them immune to it. More than half of adults, including women of childbearing age, have contracted CMV before age 40. The virus spreads through bodily fluids, including urine, saliva, mucus, and feces.
Adults who have never had CMV often catch the virus from a toddler. Up to 70% of children in daycare centers catch CMV, which means they often bring it home to their families. A pregnant woman is more likely to be affected by CMV -assuming she hasn’t had it already- if she has young children at home or if she is a teacher, a nurse, or works in a daycare center. (1)
If you get CMV while you are pregnant, you have a 1 in 3 chance of passing the virus to your unborn child, according to the March of Dimes.(1) This is called congenital CMV. About 1 in every 150 babies is born with congenital CMV, according to the U.S. Centers for Disease Control and Prevention (CDC).
The majority of the babies born with congenital CMV have no health problems. Only about one in every five babies born with CMV infection (20%) either become sick or have any lasting health problems, according to the CDC. (2) However, congenital CMV can cause premature birth, small size at birth, and hearing problems. It is also linked to microcephaly, where the baby’s head is too small. CMV is also the leading cause of non-genetic hearing loss in babies.(3)
For most children and adults, a CMV infection is very mild. Either you have mild flu-like symptoms or no symptoms at all. CMV is one of the herpes-viruses, which includes chicken pox, shingles, and the viruses that cause cold sores. Like the other herpes-viruses, CMV stays in the body for life, but a pregnant woman does not pass it on to her baby unless she catches it during her pregnancy.
How can you reduce the risk of a CMV infection?
If you work with children or in health care, or have a toddler at home, you can reduce your risk of getting CMV by washing your hands well every time you come into contact with a small child’s body fluids. This includes every time you change a diaper, wipe a runny nose, or pick up toys that a child may licked or chewed on. You should also not share forks or spoons with young children or drink from the same cup or glass while you are pregnant.
Treatment of CMV infection
If you think you may have caught CMV, tell your obstetrician or midwife. They can run a blood test to see if you have been infected. If you were infected, they will talk to you about taking a test called amniocentesis, which requires a sample of amniotic fluid from around your baby to test for the presence of CMV. A test for CMV can also be done at birth, using the baby’s saliva or blood.
There is no vaccine against CMV and there are no clear guidelines on whether all infants born with CMV need to be treated with antiviral drugs. The CDC notes that antiviral drugs is not currently recommended for babies with CMV who don’t have any signs of problems at birth.(2) However, antiviral drugs may decrease the risk of later health problems including hearing loss. Babies born with CMV should have their hearing tested regularly.
The bottom line is that you should take common sense protections that include washing your hands regularly. If you are concerned about CMV infections, talk to your obstetrician or midwife.
- March of Dimes. Cytomegalovirus and pregnancy.
- Centers for Disease Control and Prevention. Cytomegalovirus (CMV) and Congenital CMV Infection.
- Saint Louis C: CMV is a greater threat to infants than Zika, but far less often discussed. New York Times. Oct. 24, 2016.