Herpetic antivirals and risk of birth defects

January 01, 0001

Herpetic antivirals and risk of birth defects

Herpetic infections, such as herpes simplex and herpes zoster infections are common and frequently treated with antiviral drugs including acyclovir, valacyclovir, and famciclovir. However, the safety of these antivirals in pregnancy is unclear. These Danish investigators tested for links between exposure to acyclovir, valacyclovir, and famciclovir in the first trimester of pregnancy and risk of major birth defects. They used a population-based historical cohort study of 837 795 live-born infants in Denmar. Participants had no diagnoses of genetic abnormalities, birth defect syndromes with known causes, or congenital viral infections.

The researchers found: "Among 1804 pregnancies exposed to acyclovir, valacyclovir, or famciclovir in the first trimester, 40 infants (2.2%) were diagnosed with a major birth defect compared with 19 920 (2.4%) among the unexposed (adjusted prevalence odds ratios (POR), 0.89). For individual antivirals, a major birth defect was diagnosed in 32 of 1561 infants (2.0%) with first-trimester exposure to acyclovir (adjusted POR, 0.82) and in 7 of 229 infants (3.1%) with first-trimester exposure to valacyclovir (adjusted POR, 1.21). Famciclovir exposure was uncommon (n = 26), with 1 infant (3.8%) diagnosed with a birth defect. Exploratory analyses revealed no associations between antiviral drug exposure and 13 different subgroups of birth defects, but the number of exposed cases in each subgroup was small."

The researchers concluded: "In this large nationwide cohort, exposure to acyclovir or valacyclovir in the first trimester of pregnancy was not associated with an increased risk of major birth defects."

This study finds no evidence of birth defects with first trimester exposure to acyclovir or valacyclovir, but data on famciclovir was too sparse to draw conclusions.

For the full abstract, click here.

JAMA 304(8):859-866, 25 August 2010
© 2010 American Medical Association
Use of Acyclovir, Valacyclovir, and Famciclovir in the First Trimester of Pregnancy and the Risk of Birth Defects. Björn Pasternak and Anders Hviid.

Category: W. Pregnancy, Family Planning. Keywords: acyclovir, valacyclovir, famciclovir, birth defects, first trimester, cohort study, journal watch.
Synopsis edited by Dr Paul Schaefer, Toledo, Ohio. Posted on Global Family Doctor 17 September 2010

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