Do Antiviral Drugs Taken During Pregnancy Cause Birth Defects?

Recommendations of the American College of Obstetricians and Gynecologists (Obstet Gynecol 2007 Jun; 109:1489) and the CDC regarding antiviral therapy for genital herpes during pregnancy are consistent with the view that maternal exposure to such therapy is not likely to be associated with birth defects; however, supporting data are limited. To examine whether this approach is justified, researchers in Denmark used nationwide medical and prescription records from 1996 through 2008 to evaluate incidence of birth defects among women who received acyclovir, valacyclovir, or famciclovir during the first trimester.

In all, 40 of 1804 women who received antiviral drugs (2.2%) and 19,920 of 351,614 unexposed women (2.4%) had children with birth def…