New study looks at risk of birth defects with antiviral use in first trimester of pregnancy
While a number of studies have established the safety of the three widely-prescribed antiviral treatments for herpes—acyclovir, famciclovir, and valacyclovir—in general, use of these treatments in pregnancy has not been extensively investigated. Results of a new study examining data over a decade in Denmark, however, offer new reassurance. Researchers there found no association between antiviral use in the first trimester of pregnancy and an increased risk of major birth defects.
This large study used data from nationwide registries in Denmark of all infants born alive between January 1996 and September 2008. To confirm the use of antivirals by individual women, researchers used the Prescription Drug Register, which includes information on all prescriptions filled at pharmacies in Denmark. Researchers decided to use data from the registry on filled prescriptions as an indicator of drug exposure to eliminate possible errors in recall of study participants. However, they also acknowledge that, while a woman may have filled a prescription, she may not have taken it.
The study, the authors note, “has immediate clinical implications and may support informed decisions on safety when prescribing antivirals for herpes infections early in pregnancy.” They do note, however, that of the three antiviral medications studies, acyclovir was the most widely used and documented in the study, and suggest that this be the “drug of choice” in early pregnancy. Data on valacyclovir and famciclovir exposure during early pregnancy in the study was too limited for the authors to draw any definitive conclusions.