CYTOMEGALOVIRUS screening and antenatal valacyclovir treatment increased substantially in France following publication of a pivotal 2020 randomised controlled trial, according to a national retrospective study assessing maternal cytomegalovirus infection during pregnancy.
The shift in practice was not accompanied by a rise in termination of pregnancy rates, addressing one of the longstanding concerns around broader screening policies.
Cytomegalovirus (CMV) is the leading infectious cause of congenital neurosensory impairment. In France, approximately 0.4% of newborns are affected by congenital CMV infection, which can lead to psychomotor delay or sensorineural hearing loss, particularly after first-trimester maternal infection.
Maternal Cytomegalovirus Screening Increased Nationwide
Using data from the French National Reference Center for Herpesviruses database collected between 2017 and 2023, investigators examined 451 pregnancies with documented maternal CMV infection and known neonatal infection status at birth, including 220 pregnancies involving primary infection during the periconceptional period or first trimester.
The researchers found that systematic CMV screening increased from 22.0% between 2017 and 2020 to 40.0% between 2021 and 2023. Maternal requests for testing also rose from 0% to 4.2% during the same periods.
The increase followed the publication of a 2020 trial showing that valacyclovir reduced vertical transmission by two-thirds when given during first-trimester primary infection. European expert groups subsequently recommended valacyclovir for women infected during the periconceptional period or early pregnancy.
Use of antiviral therapy, predominantly valacyclovir, climbed from 27.7% before 2021 to 59.8% afterwards.
Maternal-fetal transmission occurred in79.3% of pregnancies with early primary infection, although the authors noted that this figure was likely inflated by preferential reporting of severe or confirmed cases.
Imaging Findings Shaped Pregnancy Decisions
Amniocentesis was performed in most pregnancies with first-trimester or periconceptional infection, while fetal brain MRI was reported in 56 cases. MRI abnormalities were identified in 41.9% of cases between 2017 and 2020 and in 48.0% between 2021 and 2023, with no significant difference between periods.
All recorded terminations of pregnancy involved fetuses with ultrasound or MRI abnormalities. Reported cerebral findings included ventriculomegaly, calcifications, cerebellar hypoplasia, abnormal gyration, corpus callosum abnormalities and microcephaly.
The overall termination of pregnancy rate in early maternal CMV infection was 20.7%, but fell significantly after 2020, declining from 25.9% to 13.0%. Women who did not receive valacyclovir were more likely to undergo termination than those who received treatment.
Questions Remain Around National Policy
France did not introduce national recommendations for systematic maternal CMV screening until May 2025, and screening strategies continue to vary across Europe. Concerns remain regarding maternal anxiety, adverse effects linked to high dose valacyclovir, and potential over-intervention.
The findings suggest increasing acceptance of CMV serological testing and preventive treatment in routine pregnancy care as therapeutic options become more evidence-based.
Reference
Coste-Mazeau P et al. Changing trends in prenatal screening and treatment of cytomegalovirus infection in France: 7-year national cohort study (2017–2023).
Ultrasound Obstet Gynecol. 2026;DOI:10.1002/uog.70223.
Featured image: Sergey Novikov on Adobe stock
