The Unknown Impact of Congenital Cytomegalovirus

Congenital Cytomegalovirus (cCMV) is both the most common congenital infection in the developed world (Swanson & Schleiss, 2013) and the leading cause of non-genetic hearing loss in children (Zegarac, 2017), yet the virus remains relatively unknown. In 2016, a study published in the Journal of Early Hearing Detection and Intervention revealed that only 9% of women were aware of CMV (Doutré, S., Barrett, T., Greenlee, J., & White, K., 2016), demonstrating a significant decrease from prior studies. 

Cytomegalovirus is a common viral infection, much like the everyday cold. In fact, over half of all adults have had a CMV infection by age 40. The virus is easily transmitted and preventable, living in saliva, urine, and other bodily fluids that can be quickly spread through households and early childcare settings without precautions such as frequent handwashing. In healthy adults the virus may cause no symptoms at all or it may cause mild illness, such as a fever or a sore throat. However, when a woman is infected with CMV during pregnancy the virus may be transmitted to the unborn fetus, causing the infection known as congenital cytomegalovirus

Congenital cytomegalovirus can cause a wide range of health conditions in babies. (National CMV Foundation, 2020; CDC 2020). The degree of complications caused by cCMV ranges from mild to severe, depending on the baby’s presentation at birth. Babies born asymptomatic (without any or with minimal symptoms of the virus) may have no visible delays or health impairments, or they may have hearing loss, mild vision loss, and communication delays. On the other end of the spectrum, babies born with symptomatic cCMV may present with more serious complications such as Cerebral Palsy, seizures, failure to thrive, vision and hearing loss, and in some cases, death (National CMV). 

CMV Presents in a spectrum

When we think about viruses and viral infections, our automatic assumption is that the more we hear about it, the more people it impacts. It is likely that every single person reading this article is aware of the seasonal flu and, most recently, the novel coronavirus, but are they aware of how many babies are impacted by cCMV? The Center for Disease Control estimates that approximately 1 in 200 babies are born with congenital cytomegalovirus, and 1 in 10 of those babies will be symptomatic at birth. Of the babies born symptomatic at birth, 1 in 5 will present with long-term health complications. Unfortunately, this is likely an oversimplification that underestimates the number of babies affected by cCMV. 

Here’s why…

Incidence varies by studies

Based on the statistics provided by the Center for Disease Control (CDC) the prevalence rate of congenital CMV falls around 0.5%. However, this estimate is merely that- an estimate- and actual prevalence varies across the country and between studies. In 2020, physician and CMV expert Dr. Gail Demmler-Harrison reported that the incidence of congenital CMV actually ranges between 0.2%-2.5% in the United States (Demmler-Harrison, Miller, 2020). This discrepancy between studies occurs for a variety of reasons that include, but are not limited to, the population studied, the geographical location, and the study design. In addition, some studies have found differences in the prevalence of cytomegalovirus based on race and ethnicity, with rates of infection being significantly higher among black and multiracial infants and slightly higher among Hispanic white infants (Fowler et al., 2018).

Current estimates only include live births 

The 1 in 200 babies born with congenital cytomegalovirus does not include miscarriages or stillbirths. According to Dr. Demmler-Harrison, 8% of newborns with cCMV will die in utero or as a newborn or in early infancy (Zecarac, 2017). 

Many babies with congenital cytomegalovirus are missed due to being born asymptomatic or with mild symptoms.

Approximately 90% of babies born with cCMV will have no symptoms, while 10-15% of those babies will later develop a progressive hearing loss (Fowler, 2013). To receive a cCMV diagnosis, babies must be screened within the first three weeks of life. Without this universal screening at birth, most babies born with little to no symptoms may never be diagnosed, creating a barrier between babies and the medical and educational services they may need now and in the future. 

Due to a lack of newborn screening for cCMV, the virus’s prevalence and impact are likely much higher than the current estimates reflect. The need for increased awareness and universal newborn screening of congenital cytomegalovirus at birth is critical. With proper public awareness of the virus and its transmission, pregnant and expectant mothers will have the knowledge and resources to prevent congenital cytomegalovirus. Additionally, the proper identification of both asymptomatic and symptomatic infants infected with cCMV at birth will allow parents the opportunity to access appropriate treatment, therapies and educational services, and resources as soon as possible, thus leading to better outcomes for the child. 

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About Cytomegalovirus and Congenital CMV Infection. (2020, August 18). Retrieved January 14, 2021, from
Demmler-Harrison, G. J., Miller, J. A., & Houston Congenital Cytomegalovirus Longitudinal Study Group (2020). Maternal cytomegalovirus immune status and hearing loss outcomes in congenital cytomegalovirus-infected offspring. PloS one, 15(10), e0240172. 
Doutre, S., Barrett, T., Greenlee, J., White, K. (2016). Losing Ground: Awareness of Congenital Cytomegalovirus in the United States. Journal of Early Hearing Detection and Intervention, 1(2):39-48.  
Fowler K. B. (2013). Congenital cytomegalovirus infection: audiologic outcome. Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 57 Suppl 4(Suppl 4), S182–S184.
Fowler, K. B., Ross, S. A., Shimamura, M., Ahmed, A., Palmer, A. L., Michaels, M. G., Bernstein, D. I., Sánchez, P. J., Feja, K. N., Stewart, A., & Boppana, S. (2018). Racial and Ethnic Differences in the Prevalence of Congenital Cytomegalovirus Infection. The Journal of pediatrics, 200, 196–201.e1.
Possible Outcomes. (n.d.). Retrieved January 14, 2021, from
Swanson, E. C., & Schleiss, M. R. (2013). Congenital cytomegalovirus infection: new prospects for prevention and therapy. Pediatric clinics of North America, 60(2), 335–349.
Žegarac, J. (2019, January 11). CMV Infection in Mothers and Infants: Diagnostic and Treatment Challenges. Retrieved January 14, 2021, from