The term “people who are pregnant” is used throughout the document. We recognize and respect that individuals and families may use other preferred terminology, such as "expectant mothers" or "birthing people".
Most babies born with congenital cytomegalovirus (cCMV) will not have symptoms or long-term health problems. Some babies who do experience symptoms of cCMV may benefit from anti-viral medication or other interventions. Awareness of cCMV is important as there are simple day-to-day strategies that can help reduce the risk of having a baby with cCMV.
What is CMV?
CMV is a member of the herpesvirus family which includes herpes simplex virus (HSV), varicella-zoster virus and Epstein Barr virus (EBV or mononucleosis). These viruses all establish life-long latency after infection. This means that after a person is infected with CMV or any of these other herpesviruses, the virus remains inside the body without causing symptoms and may reactivate occasionally. In the case of CMV, these reactivations generally do not cause problems unless the person’s immune system is compromised by medication or disease.
First-time infection with CMV is called primary infection. The reactivation of a previous infection or infection with a different strain of the virus is called non-primary infection. People who are pregnant can transmit CMV to the fetus during primary or non-primary infections. The risk of complications to the fetus is greatest if maternal infection occurs during the first trimester of pregnancy.
CMV is shed in body fluids such as saliva, urine, breast milk, semen and blood. CMV is found in particularly high amounts in young children’s saliva and urine. Avoiding exposure to bodily fluids during pregnancy can help reduce the risk of congenital CMV for your baby.
Signs of cCMV infection during pregnancy
In most cases, a fetus does not show signs of cCMV infection. Fetal signs that are sometimes identified on prenatal ultrasounds include:
- intrauterine growth restriction (IUGR; poor growth measurements for gestational age)
- changes in a fetus’s brain
- small head size (microcephaly)
- big liver or spleen
- echogenic bowel
Signs of cCMV infection at birth
Approximately 85 to 90 per cent of infants with cCMV infection will not show any signs or symptoms of the infection at birth. Signs and symptoms that may be present include:
- premature birth
- rash (purpura or petechia)
- low birth weight
- small head size (microcephaly)
- enlarged liver or spleen
- yellow skin and eyes (jaundice)
- sensorineural hearing loss
Signs of cCMV that may develop later
A small number of babies who have cCMV who appear healthy at birth may develop signs of infection later on. The most common of these late-occurring signs are sensorineural hearing loss and developmental delay. A small number of children may also develop vision problems.
Congenital CMV screening and testing
In 2019, the Ontario Infant Hearing Program (IHP) added risk factor screening to the provincial hearing screening program. Risk factor screening uses the dried blood spot sample collected after birth to screen for CMV. All babies born in Ontario should be offered this dried blood spot screen after birth.
The dried blood spot is tested for multiple diseases, including CMV. In 2024, some hospitals started screening for CMV with saliva samples in addition to the screening with the dried blood spot sample on a trial basis. Babies who test positive for CMV on their dried blood spot or saliva sample will be contacted by Newborn Screening Ontario (NSO) to arrange for further testing and evaluation.
Babies who are born with signs of CMV or who had signs of CMV prenatally should have their urine tested after birth to confirm if CMV infection is present. Babies who fail their newborn hearing screen or who have hearing loss with unclear cause should be tested for CMV. Ideally, these tests are completed before babies are three weeks old as after that time, it is not possible to be sure if the infection was acquired before or after birth.
How is cCMV treated?
Antiviral treatment
Babies who have symptoms of cCMV are referred to an infectious disease specialist to determine if they should receive an antiviral medication. For some of these babies, treatment with antiviral medication for six months has been shown to help preserve hearing and improve developmental outcomes. Babies who receive antiviral treatment need to be monitored with regular blood work.
Other interventions
A child with cCMV will have regular monitoring of growth and development, and they will have ongoing hearing testing to help identify concerns as early as possible. Identifying hearing loss allows affected children to get the support and services they need to learn language and optimize development. Depending on each individual scenario, hearing loss can be treated with amplification (hearing aids) or cochlear implantation. Families are also connected to language development services to help with language development, be it spoken language and/or sign language.
How to prevent the spread of CMV
No special isolation precautions are required for children with congenital CMV in hospital or daycare settings. A child with cCMV infection should not be treated differently from other children. However, you should follow standard precautions including hand hygiene when caring for all children, particularly after diaper changes or contact with saliva. People who are pregnant or immunocompromised should be especially mindful of these precautions.
How to reduce the risk of cCMV during pregnancy
CMV is very common and easy to catch. People who are pregnant can reduce the risk of cCMV by using the following measures:
- Wash hands with soap and water frequently, particularly after changing diapers or touching saliva.
- Avoid sharing utensils, food and drinks with young children.
- Do not share toothbrushes.
- Avoid putting a child’s pacifier in your mouth.
- Frequently clean toys, pacifiers or other objects that may have come in contact with body fluids.
Hearing loss
The most common long-term complication of cCMV infection is sensorineural hearing loss. This hearing loss may be present at birth or may develop over time. The hearing loss varies in severity from mild to profound and may affect one or both ears. In some cases, hearing loss can worsen over time.
Other complications
Other complications from cCMV infection are much less common but may include developmental delay or vision problems.
Caring for your child with cCMV at home
In general, children with cCMV do not require special care at home.
If your child has hearing loss, it is important to encourage them to use their amplification device or cochlear implant to improve language acquisition and associated brain development.
If your child has developmental delays, it is important to stay connected to health-care providers and your child’s school to ensure they have access to the supports and resources they need.
Follow-up care for cCMV
Diagnosing, treating and monitoring children with cCMV can help improve health outcomes. It is important for children diagnosed with cCMV to continue regular hearing and developmental assessments as some problems can develop over time, even if there were no concerns on initial assessment. In Ontario, hearing screening and developmental surveillance continues until age 5 for children diagnosed with cCMV.
Children who are found to have symptoms of cCMV may benefit from additional services such as speech and language pathology (SLP), physiotherapy, occupational therapy, social work, audiology, otolaryngology (ENT) and ophthalmology.
Further research is required to learn more about long-term outcomes for babies with cCMV.
When to see a health-care provider during cCMV treatment
The main adverse effect of the antiviral treatment for cCMV is neutropenia (low neutrophil count). Neutrophils are a type of white blood cell that help to fight infection. Your child will need to be closely monitored throughout treatment to manage any adverse effects from the medication. If your child does develop significant neutropenia, your health-care provider may recommend that you stop the antiviral medication temporarily and advise that you seek medical care if fever develops.
Resources
CMV Canada – A national charity that raises awareness of CMV and offers resources to families affected by cCMV.
Newborn Screening Ontario – The provincial screening program offers educational information on cCMV as well as screening and follow up.
References
Barton, M., Forrester, M., and McDonald, J. (2020). Update on congenital cytomegalovirus infection: Prenatal prevention, newborn diagnosis, and management. Canadian Paediatric Society, Infectious Diseases and Immunization Committee. Paediatric Child Health, 25(6), 395-396. doi: 10.1093/pch/pxaa083.
Gantt, S., Bitnun, A., Renaud, C., Kakkar, F., and Vaudry, W. (2017). Diagnosis and management of infants with congenital cytomegalovirus infection. Paediatrics & Child Health, 22(2), 72-74. doi: 10.1093/pch/pxx002
Kimberlin, D., Jester, P., Sánchez, P., Ahmed, A., Arav-Boger, R., Michaels, M., Ashouri, N., Englund, J., Estrada, B., Jacobs, R., Romero, J., Sood, S., et al., for the National Institute of Allergy and Infectious Diseases Collaborative Antiviral Study Group. (2015). Valganciclovir for symptomatic congenital cytomegalovirus disease. The New England Journal of Medicine, 372(10), 933-943. doi: 10.1056/NEJMoa1404599
Ontario Infant Hearing Program and Newborn Screening Ontario. Information for parents/guardians: My baby has a positive cytomegalovirus (CMV) screening result. Retrieved from: https://www.newbornscreening.on.ca/media/yyfc12wd/cytomegalovirus-and-your-baby-v3-final-2023.pdf