New Prenatal Test Could Stop Common Cause of Birth Defects

WASHINGTON – January 06, 2026 – A routine blood test already offered to millions of expectant parents could soon double as a powerful tool to prevent permanent hearing loss and developmental disabilities in newborns. A groundbreaking study published today indicates that a low-cost form of noninvasive prenatal screening (NIPS) can effectively identify pregnant women carrying cytomegalovirus (CMV), a common but dangerous infection that is a leading cause of non-genetic birth defects.

The findings, which appear in a special issue of the Association for Diagnostics & Laboratory Medicine's (ADLM's) Clinical Chemistry journal, have the potential to reshape prenatal care by providing a clear path from early detection to effective intervention, a combination that has been missing for decades.

A Breakthrough in Early Detection

The new research details how a team in Belgium leveraged existing NIPS technology to hunt for viral DNA. NIPS is already a standard part of prenatal care for many, used to screen for chromosomal abnormalities like Down syndrome by analyzing small fragments of DNA circulating in a mother’s blood. This new application expands its utility into the realm of infectious disease.

Led by Dr. Geert A. Martens, the research team analyzed NIPS data from 22,333 pregnancies between late 2019 and early 2025. Using a cost-effective method called low-pass whole genome sequencing, they scanned the samples for genetic material from non-human sources. They found cell-free DNA from CMV in 2.1% of the pregnancies, a figure consistent with known infection rates.

Crucially, the amount of viral DNA detected by the NIPS test correlated strongly with confirmed infections in both the mothers and their babies. The risk for congenital CMV infection—when the virus is passed to the fetus during pregnancy—was highest in pregnancies with the most viral DNA. "Our study is the first to directly link NIPS-derived CMV read counts to both maternal serostatus and confirmed cCMV [congenital CMV] outcomes from a systematic newborn screening program," the researchers stated, underscoring the real-world applicability of their findings in a large-scale setting.

From Detection to Prevention

The significance of this early detection method is magnified by recent advances in treatment. Congenital CMV occurs in about 1 in 150 live births globally, and up to 20% of infected infants suffer irreversible consequences, including hearing and vision loss, microcephaly, and neurodevelopmental delays.

For years, the lack of an effective prenatal therapy was a primary reason for not screening for CMV during pregnancy. That landscape began to shift dramatically in 2020 with research demonstrating that the antiviral drug valacyclovir, when given to women with a primary CMV infection in their first trimester, could reduce the rate of transmission to the fetus by more than 70%.

While valacyclovir is not yet formally approved by the U.S. Food and Drug Administration for this specific use, its efficacy has led many maternal-fetal medicine specialists to prescribe it "off-label." Multiple studies have shown that high-dose valacyclovir not only lowers the transmission rate but also significantly increases the proportion of infected babies who are born without symptoms, from 43% in untreated cases to over 80% in treated ones. The ability to identify at-risk pregnancies as early as 12-14 weeks' gestation, as demonstrated in the new study, creates a critical window for this potentially preventative treatment.

Challenging Long-Standing Guidelines

The new research lands squarely in the middle of a long-standing debate over prenatal CMV screening. Major health organizations, including the American College of Obstetricians and Gynecologists (ACOG) and the Centers for Disease Control and Prevention (CDC) in the United States, do not currently recommend universal routine screening for CMV in pregnant women.

This guidance has historically been based on several factors: the difficulty in distinguishing a new, high-risk infection from a past one using traditional antibody tests, the inability of older tests to predict which babies would be harmed, and the absence of a proven therapy. The new NIPS method, however, appears to address these barriers. By quantifying viral DNA, it offers a more direct measure of active infection, and its integration into an existing, low-cost screening platform makes it a more feasible option for widespread use.

"Given its low cost and high throughput, [the integration of CMV DNA testing] into routine aneuploidy screening is a powerful complement to serology, poised to improve the identification of pregnancies that may benefit from antiviral therapy," the study's authors wrote. This new capability puts pressure on medical bodies to re-evaluate their positions, a move already underway in parts of Europe and Israel where serological screening is more common. The combination of a reliable, scalable screening test and an effective intervention may finally tip the scales in favor of making CMV screening a standard part of prenatal care worldwide.

Empowering Parents and Reshaping Prenatal Care

Beyond policy and protocols, the study's findings represent a significant step forward for expectant parents. A congenital CMV diagnosis often comes as a shock after a baby is born with complications, leaving families to navigate a difficult "diagnostic odyssey." Early awareness could transform this experience, replacing uncertainty with information and proactive choices.

The cost-effectiveness of integrating CMV detection into existing NIPS workflows is also a critical factor. The long-term societal and healthcare costs of caring for a child with severe disabilities from congenital CMV can be substantial, running into millions of dollars over a lifetime. Preventing even a fraction of these cases through early screening and treatment could result in significant savings and, more importantly, reduce human suffering.

While the study's authors note that more research is needed to fully define the clinical pathway from a positive NIPS screen to treatment, this breakthrough opens a new frontier in perinatal diagnostics. By harnessing the power of a test already in hand, the medical community may be on the verge of neutralizing one of the most common infectious threats to newborns, offering a healthier start to thousands of babies each year.