Most newborns leave the hospital after a quick hearing screen and a clean bill of health. Parents rarely hear about a common virus that can quietly affect hearing later: cytomegalovirus (CMV). When a baby is born already infected, doctors call it congenital CMV (cCMV). Knowing a few practical facts—especially about hearing checks and the early testing window—can help you ask the right questions.
What is congenital CMV?
CMV is a common virus in the same family as chickenpox. Healthy children and adults often catch it with mild symptoms or none at all. If someone becomes infected during pregnancy and the virus reaches the baby before birth, that is congenital CMV. According to the U.S. Centers for Disease Control and Prevention (CDC), about 1 in 200 babies is born with congenital CMV, and about 1 in 5 of those babies will have birth defects or longer-term health problems such as hearing loss.
Why hearing matters so much
Most babies with cCMV look well at birth. Still, CMV can damage the inner ear. A baby may be born hard of hearing, or hearing can change months or even years later—even after a passed newborn screen. The American Academy of Pediatrics explains on HealthyChildren.org that up to half of newborns who have signs of cCMV at birth, and about 15% of those without signs, may later have hearing changes. Regular hearing checks catch problems early, when support for language helps most.
The testing window parents should know
If your newborn does not pass the hospital hearing screen, ask whether a cCMV test is needed. A urine or saliva test (sometimes blood) done within about the first 21 days of life can confirm infection that began before birth. After roughly three weeks, it becomes harder to tell congenital infection apart from CMV caught after birth. Your paediatrician can guide next steps if pregnancy CMV exposure was known, or if there are other newborn concerns.
What parents can do—during pregnancy and after birth
There is no routine CMV vaccine yet, and doctors do not usually screen every pregnant person for CMV. Simple habits can still lower everyday exposure, especially around toddlers who often shed the virus in saliva and urine:
- Wash hands with soap after nappy changes, wiping noses or drool, and before eating.
- Avoid sharing food, drinks, utensils, toothbrushes, or pacifiers with young children.
- Kiss on the forehead rather than on the mouth when you want to be extra careful during pregnancy.
- Follow through on hearing screens and any recommended follow-up visits in the first months of life.
When to seek care
Contact your paediatrician promptly if your newborn did not pass the hearing screen, if you were told about possible CMV in pregnancy, or if you notice early hearing red flags—such as not startling to loud sounds, not turning to a voice by about 6 months, or delayed babbling. Babies diagnosed with cCMV may need hearing and vision follow-up; some with clearer disease at birth may be considered for antiviral medicine under specialist care. If you want a face-to-face review of newborn hearing results or CMV questions, you can book an appointment.
A calm parent takeaway
Congenital CMV is common, and most affected babies do well. Complete newborn hearing screening, ask about CMV testing when a screen is failed or risk is known, and keep follow-up appointments so any hearing change is found early. Your child’s care team can interpret results and plan support—you do not have to figure this out alone.
This article is for general information and parent education. It is not a substitute for personal medical advice. Always discuss your child’s symptoms or test results with a qualified clinician.
Sources: CDC — CMV in Newborns (Congenital CMV); CDC — Congenital CMV and Hearing Loss; HealthyChildren.org / AAP — Can CMV cause hearing loss in babies?; AAP — Congenital Cytomegalovirus (cCMV).
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