Cytomegalovirus (CMV) is a common virus that can infect people of all ages. The virus can also be passed to the fetus before birth if a pregnant person is infected. This is called "congenital" CMV (cCMV).
Congenital CMV is the most common infectious cause of deafness for babies. CMV infection during pregnancy can affect the inner ear and lead to hearing loss for the baby. The condition is usually detected at birth but can be found later.
Here is what we know about CMV infection during pregnancy and what to expect if a baby is born with cCMV.
How likely is it that a CMV infection in pregnancy will be passed to the developing baby?
If a person is infected with CMV for the first time while they are pregnant, there is about a 30% to 40% chance it will pass to the developing fetus. Once CMV is in a person's body, the virus stays there for life, usually in a dormant (inactive) state.
The infection can flare up again (reactivate). It is also possible to be infected with another strain of the virus. CMV infection can be passed to the developing fetus following infection with a new strain or during times when the virus flares up; the risk is highest with the first infection, though.
An infection during the first trimester of pregnancy has the highest risk of complications for the baby.
What are the signs of congenital CMV?
About 1 in 10 babies have signs at birth. Most babies born with cCMV do not have any signs.
Signs of the infection at birth may include:
- Rash
- Jaundice (yellowing of the skin or whites of the eyes)
- Small head
- Low birth weight
- Enlarged liver and spleen
- Seizures
- Damage to the retina of the eye
What are the health conditions that can develop in babies with cCMV?
Up to half of newborns with signs and 15% without signs of cCMV at birth will have hearing loss.
Other long-term serious problems from cCMV include developmental and motor delay, vision loss, small head, muscle weakness and seizures. Children with cCMV are more likely to be diagnosed with autism spectrum disorder, according to a recent study. More research is needed to understand this link.
How do newborns get tested for CMV infection?
In the United States, all newborns should have a hearing screening before leaving the hospital or birthing center. If they are not screened, it is important that they get tested during their first month of life.
If your newborn does not pass a hearing screening, they should have a follow-up visit right away with an audiologist.
A urine or saliva test can be done within the first 3 weeks of birth to check for congenital CMV. If your newborn does not pass the hearing screening, ask if they should be tested for cCMV. There are genetic causes and other diseases during pregnancy that can also cause a baby to be born deaf or hard of hearing. Your pediatrician will be able to direct an evaluation for these causes.
If a newborn has a cCMV infection, an antiviral medication can be prescribed. The medication may help reduce the severity of hearing loss. In addition to medication, babies with cCMV may benefit from developmental monitoring and early intervention services.
The American Academy of Pediatrics recommends that children born with congenital CMV get a full hearing test. They should continue to get regular hearing checks at ages 4, 6, 9, 12, 15, 18, 24 and 30 months. In addition, a standard hearing test is recommended for all children at ages 4, 5, 6, 8 and 10 years old. If a child is deaf or hard of hearing they should be evaluated by a pediatric otolaryngologist (ENT specialist) and will also require services such as speech therapy or occupational therapy.
Remember
CMV is the most common infectious cause of birth defects in the United States. If you suspect that your baby may have congenital CMV, do not wait until your baby's next checkup. It's important to ask your child's pediatrician about your concerns. Acting early makes a big difference.
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