Congenital CMV Infection
What is Congenital CMV Infection?
Congenital CMV infection happens when a baby is born with cytomegalovirus, or CMV, passed from mother to child during pregnancy. CMV is a common virus in the herpes family that usually causes mild or no symptoms in healthy adults. When a pregnant woman becomes infected with CMV for the first time, the virus can cross the placenta and infect the developing baby.
This condition is the most common viral infection present at birth in the United States. About 1 in 200 babies are born with congenital CMV each year. Most infected babies appear healthy at birth, but some develop serious health problems either immediately or later in childhood. The severity depends on when during pregnancy the infection occurred and how the baby's immune system responds.
CMV stays in the body for life after infection, usually in a dormant state. Most people with CMV never know they have it. The virus becomes a concern mainly during pregnancy, especially if a woman gets infected for the first time while carrying a baby. Understanding CMV helps pregnant women and those planning pregnancy protect their developing babies.
Symptoms
- Hearing loss, which may be present at birth or develop later in childhood
- Vision problems or blindness
- Small head size, known as microcephaly
- Seizures
- Intellectual disability or developmental delays
- Liver or spleen enlargement
- Yellow skin and eyes, called jaundice
- Purple skin rashes or spots
- Low birth weight
- Pneumonia
About 90% of babies born with congenital CMV have no symptoms at birth. Some of these children will develop hearing loss or other problems months or years later. Only about 10% of infected babies show symptoms at birth, but these babies often have more severe complications.
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Causes and risk factors
Congenital CMV infection occurs when a pregnant woman passes the cytomegalovirus to her developing baby. The virus spreads through body fluids including saliva, urine, blood, breast milk, and genital secretions. Pregnant women most commonly catch CMV from close contact with young children who shed the virus in their saliva and urine. Women who work in childcare settings or have young children at home face higher risk. The virus can also spread through sexual contact or blood transfusions.
The risk of passing CMV to the baby is highest when a pregnant woman gets infected for the first time during pregnancy, called a primary infection. Women who already had CMV before pregnancy can experience reactivation or reinfection, but these situations rarely cause congenital infection. Other risk factors include having multiple sexual partners, not practicing good hygiene after contact with young children, and giving birth at a younger age. Women under 30 and those with more than one child have higher rates of primary CMV infection during pregnancy.
How it's diagnosed
Doctors diagnose congenital CMV infection in newborns by testing saliva, urine, or blood within the first three weeks of life. Testing must happen during this early window because later testing cannot distinguish congenital infection from infection acquired after birth. The most reliable method is a CMV DNA or culture test from these samples. A positive result during the first three weeks confirms the baby was infected before birth.
For pregnant women, blood tests can check CMV antibody levels to determine infection status. Two types of antibodies matter: IgM antibodies suggest recent infection, while IgG antibodies indicate past infection or immunity. High levels of CMV IgG in a pregnant woman can point to an active infection. High CMV IgM levels may signal a recent infection that could lead to congenital CMV in the baby. However, these specialized CMV antibody tests are not part of routine prenatal care. Talk to your doctor about testing options if you think you may have been exposed to CMV during pregnancy.
Treatment options
- Antiviral medications like valganciclovir for babies with symptoms, especially those affecting the central nervous system
- Regular hearing tests throughout childhood to catch hearing loss early
- Vision screenings and eye exams to monitor for problems
- Physical therapy, occupational therapy, and speech therapy for developmental delays
- Hearing aids or cochlear implants for children who develop hearing loss
- Special education services and early intervention programs
- Regular checkups with specialists including neurologists, audiologists, and ophthalmologists
- Prevention during pregnancy through handwashing after contact with young children's saliva or urine
- Avoiding sharing food, drinks, or utensils with young children when pregnant
- Proper hygiene when changing diapers or wiping noses
Frequently asked questions
There is no cure for congenital CMV infection because the virus stays in the body for life. However, antiviral medications can help manage symptoms in babies with severe infections, especially during the first six months of life. Early treatment may improve hearing and developmental outcomes. Most infected babies without symptoms at birth do well without treatment, though they need monitoring for hearing loss.
About 1 in 200 babies in the United States are born with congenital CMV infection, making it the most common viral infection present at birth. This equals roughly 20,000 to 30,000 babies each year. The infection is more common than other well-known congenital conditions but receives less public attention. Most people have never heard of congenital CMV despite its frequency.
No, most babies born with congenital CMV have no symptoms at birth and develop normally. About 90% of infected babies appear healthy at birth. Among those with symptoms, severity varies widely from mild to severe. The risk of transmission and severity depends on when during pregnancy infection occurs, with first-trimester infections carrying higher risk of complications.
CMV testing is not part of routine prenatal care, but some women choose to get tested before pregnancy. Knowing your CMV status can help you understand your risk. Women who test negative before pregnancy should take extra precautions to avoid infection during pregnancy. Talk to your doctor about whether CMV testing makes sense for your situation.
Prevention focuses on good hygiene practices, especially around young children. Wash your hands thoroughly with soap and water after contact with children's saliva, urine, or diapers. Avoid sharing food, drinks, utensils, or toothbrushes with young children. Do not put a child's pacifier in your mouth. These simple steps can significantly reduce your risk of catching CMV during pregnancy.
IgM antibodies appear first when someone gets a new CMV infection, usually within a few weeks. High IgM levels suggest a recent infection. IgG antibodies develop later and remain in the blood for life, indicating past infection or immunity. During pregnancy, high IgM levels are more concerning because they may signal a new infection that could pass to the baby.
Yes, CMV can be present in breast milk and passed to babies through breastfeeding. However, this postnatal transmission is different from congenital infection and rarely causes problems in full-term healthy babies. For premature or very low birth weight infants, doctors may recommend special handling of breast milk. The benefits of breastfeeding usually outweigh the small risk of CMV transmission for healthy newborns.
CMV can damage the developing inner ear and hearing nerve, even in babies who have no other symptoms at birth. Hearing loss occurs in about 10 to 15% of babies born with congenital CMV. It can be present at birth or develop gradually during the first few years of life. This is why regular hearing screenings are so important for all children born with CMV, even those who seem healthy.
No, children with congenital CMV do not need to be isolated from other children. While they may shed the virus in saliva and urine for years, CMV is not highly contagious. Basic hygiene practices like handwashing are enough to prevent spread. These children can safely attend daycare and school. Family members and caregivers should simply practice good hand hygiene after contact with the child's body fluids.
Yes, but the risk is much lower than with a new infection during pregnancy. Women with previous CMV infection have antibodies that provide some protection. However, the virus can reactivate or a woman can get infected with a different CMV strain. These secondary infections rarely cause congenital CMV and when they do, symptoms are usually milder than with primary infections during pregnancy.