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August 25, 2010

Acyclovir Exposure and Birth DefectsAn Important Advance, But More Are Needed

Author Affiliations

Author Affiliations: Division of Epidemiology, Statistics & Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland.

JAMA. 2010;304(8):905-906. doi:10.1001/jama.2010.1214

Twenty-two percent of pregnant women are seropositive for herpes simplex virus1 and 2% of susceptible pregnant women acquire a primary herpes simplex virus infection.2 Data on the use of acyclovir and valacyclovir to treat infected women are extremely scarce. The Slone Epidemiology Center, Boston, Massachusetts, statistics on normal pregnancies indicate that approximately 2 per 1000 pregnancies are exposed to each drug during organogenesis (A. Mitchell and C. Louik, Slone Epidemiology Center at Boston University, written communication, July 14, 2010). Thus, each year in the United States approximately 15 000 conceptuses are potentially exposed to these drugs, yet little information is available on their teratogenicity. Until now, only relatively small studies had evaluated the potential teratogenicity of acyclovir and related drugs.36 Although these studies generally showed no teratogenic effects, they were underpowered to answer the question definitively.

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