Congenital CMV (congenital cytomegalovirus) is a viral infection that a baby is born with after catching cytomegalovirus (CMV) from their mother during pregnancy.

What is congenital CMV?

  • CMV is a common herpes-family virus that many adults carry, often with mild or no symptoms.
  • When a pregnant person has CMV and it crosses the placenta, the baby can be infected before birth; this is called congenital CMV because it is present at birth.
  • It is the most common congenital infection worldwide and a leading cause of non‑genetic (nonhereditary) sensorineural hearing loss in children.

In simple terms: congenital CMV = baby infected with CMV in the womb, which can sometimes affect hearing, vision, brain development, and overall health.

How babies get congenital CMV

  • CMV is spread through body fluids like saliva, urine, blood, semen, and breast milk in everyday life.
  • Congenital CMV happens when an infected mother passes CMV through the placenta to the fetus during pregnancy.
  • The risk of more severe disease is higher if the mother has a primary CMV infection (first time ever) in early pregnancy.
  • Mothers often have no noticeable CMV symptoms, so they may not know they were infected.

Symptoms in newborns

Most babies with congenital CMV look healthy at birth and have no obvious symptoms.

Asymptomatic babies (the majority)

  • Around 85–90% of newborns with congenital CMV are asymptomatic at birth.
  • Even in this group, some may later develop hearing loss or mild developmental differences, which is why follow‑up is important.

Symptomatic babies

A smaller group has clear signs at birth, which can include:

  • Low birth weight or growth restriction.
  • Small head size (microcephaly).
  • Jaundice (yellowing of skin and eyes).
  • Enlarged liver and spleen (hepatomegaly, splenomegaly).
  • Rash or tiny purple spots (petechiae, “blueberry muffin” appearance).
  • Eye problems such as inflammation of the retina (retinitis).
  • Seizures or other neurologic signs.

Symptomatic congenital CMV carries a small but real risk of death in the newborn period, estimated around 7–12% in severe cases.

Possible long‑term effects

Even after the newborn period, congenital CMV can have lasting effects, especially in babies who were symptomatic at birth.

Possible long‑term issues include:

  • Sensorineural hearing loss (mild to profound, sometimes progressive or late‑onset).
  • Vision loss or visual impairment (from retinal damage).
  • Developmental delay or intellectual disability.
  • Motor problems, including cerebral palsy–like movement issues in some children.
  • Seizure disorders and learning difficulties.

Many children, especially those who were asymptomatic, may have normal development with little or no long‑term impact, but they still need monitoring for hearing and development.

How congenital CMV is diagnosed

  • To confirm congenital infection, CMV testing must be done in the first 3 weeks of life, usually on urine, saliva, or sometimes blood.
  • After 3 weeks, it becomes harder to tell if CMV was acquired after birth or in the womb.
  • If congenital CMV is suspected, doctors may also order:
* Hearing tests
* Eye examination
* Brain imaging (such as cranial ultrasound or MRI)
* Blood tests and ultrasound of organs

Early diagnosis matters because treatment and close follow‑up can improve outcomes, especially for hearing and neurodevelopment.

Treatment and follow‑up

There is no simple “cure,” but there are treatments that can reduce the impact of the infection in some babies.

  • For certain symptomatic infants (especially with central nervous system or hearing involvement), doctors may recommend antiviral medications such as valganciclovir for several months.
  • These medicines can help improve or stabilize hearing and neurodevelopmental outcomes in some cases but require close monitoring for side effects like low blood counts.
  • All infants with congenital CMV generally need:
* Regular hearing checks in early childhood
* Developmental assessments (speech, motor, learning)
* Follow‑up with pediatric specialists (infectious disease, audiology, neurology, ophthalmology as needed)

Can congenital CMV be prevented?

There is no licensed CMV vaccine yet, although it is an active area of research and a frequent topic in medical news and professional forums.

Practical ways to lower CMV risk in pregnancy focus on hygiene:

  • Wash hands often with soap and water, especially after changing diapers, wiping a child’s nose or drool, or handling toys.
  • Avoid sharing food, drinks, utensils, toothbrushes, or pacifiers with young children.
  • Try not to put a toddler’s pacifier in your own mouth, and minimize direct contact with saliva (like kissing on the lips) if you are pregnant.

These measures are especially emphasized for people who work with or care for young children, such as daycare workers, because CMV is common in that group.

Quick FAQ‑style recap (for “what is congenital CMV”)

  1. What is congenital CMV?
    A CMV infection a baby already has at birth after catching the virus in the womb.
  1. Is it common?
    Yes. It is the most common congenital infection globally and a major cause of nonhereditary hearing loss in children.
  1. Does every infected baby get sick?
    No. Most have no symptoms at birth, but some develop issues later (especially hearing loss). A smaller group is clearly sick at birth.
  1. Can it be treated?
    Some symptomatic babies benefit from antiviral treatment plus careful, long‑term follow‑up.
  1. Can it be prevented?
    There is no vaccine yet, but careful hygiene and avoiding contact with certain body fluids from young children during pregnancy can reduce risk.

Bottom note: Information gathered from public medical resources and clinical references available on the internet and summarized here in plain language.