Cytomegalovirus (CMV) Is Now Detectable via Non-Invasive Prenatal Testing

CMV is the most common intrauterine infection with birth prevalence at approximately one in 150–200 in the United States. Congenital CMV (cCMV) is the most significant infectious cause of congenital and delayed-onset sensorineural hearing loss and of many other neurodevelopmental and physical morbidities.

Historically, prenatal screening for CMV has not been an accepted practice guideline, mostly because if detected, the infection could not be safely prevented for the baby. A recent study, however, reported that high dose valacyclovir safely and effectively reduced the transmission from mothers with a primary first trimester infection to their unborn child, from 35 percent to 10 percent (D’Antonio et al., 2023).  

Recently, scientists in Belgium discovered a method to identify both pregnancies at risk for primary CMV infection as well as predict which of those women were more likely to pass the virus on to their unborn child. Retrospectively, researchers looked at non-invasive prenatal screening (NIPS) bloodwork of more than 20,000 women, collected at 12-weeks gestation. The screening analyzed the mother’s DNA as well as the fetus’s, searching for viral material indicating the mother had an infection. These results were then used to identify and quantify the mother’s viral load, which showed very strong correlations with primary infections and the likelihood of passing CMV to the baby (cCMV).  The authors conclude that their work enables the identification of pregnancies that may benefit from antiviral therapy. 

References

D’Antonio, F., Marinceu, D., Prasad, S., & Khalil, A. (2023). Effectiveness and safety of prenatal valacyclovir for congenital cytomegalovirus infection: systematic review and meta‐analysis. Ultrasound in Obstetrics & Gynecology, 61(4), 436-444.

Herroelen, P. H., Swaerts, K., Descheemaeker, P., Claerhout, P., Vanderstichele, A., et al. (2025). Universal screening of cytomegalovirus viral load by low-pass whole-genome sequencing in first-trimester pregnancy: clinical validation. Clinical Chemistry, 72(1), 173–182.