TUESDAY, Aug. 24 (HealthDay News) -- Pregnant women who take
antiviral drugs against the herpes virus should not worry that
their use will cause birth defects, Danish researchers report.
More than 1 percent of women develop herpes simplex during the
first trimester of pregnancy. And while the use during pregnancy of
antiviral drugs such as acyclovir (Zovirax), valacyclovir (Valtrex)
and famciclovir (Famvir) are believed to be safe, data on their use
in early pregnancy has been limited, the researchers noted.
But the new analysis suggests that "pregnant women needing
treatment for a herpes infection in the first trimester can use
antivirals without concern about birth defect risk," said lead
researcher Dr. Bjorn Pasternak, from the department of epidemiology
research at the Statens Serum Institut in Copenhagen.
Acyclovir was the most commonly used antiviral, and should be
the antiviral drug of choice in the treatment of herpes infections
in early pregnancy, Pasternak said.
"More research is however needed with regard to use of antiviral drugs in pregnancy and the risk of other adverse fetal outcomes, such as growth restriction, preterm birth and spontaneous abortion," he said.
The report, funded by the Danish Medical Research Council and
the Lundbeck Foundation, is published in the Aug. 25 issue of the
Journal of the American Medical Association.
For the study, Pasternak and colleague Dr. Anders Hviid, also
from the Statens Serum Institut, collected data on almost 840,000
births in Denmark from January 1996 to September 2008.
The women in the study had no chromosomal abnormalities, genetic
syndromes, birth defect syndromes, or congenital viral infections,
the researchers noted.
Among the more than 1,800 women exposed to acyclovir,
valacyclovir or famciclovir during their first trimester, 40
infants (2.2 percent) had a major birth defect, compared with
19,920 infants (2.4 percent) born to women not exposed to these
drugs, the researchers found.
Based on these numbers, Pasternak and Hviid concluded that the
antiviral drugs were not associated with birth defects.
For women taking acyclovir, the most commonly prescribed
antiviral, there were 32 cases of birth defects among 1,561 exposed
to the drug (2 percent), compared with 2.4 percent of the birth
defects among women not exposed acyclovir, they noted.
Among women taking valacyclovir there were seven cases of birth
defects among 229 infants (3.1 percent), a rate that was not
significantly higher than that of women not exposed to the drug.
For famciclovir, there was one case of a major birth defect among
the 26 women taking the drug (3.8 percent), but the researchers
note that the use of famciclovir was uncommon.
Further analysis did not find any associations between these
antiviral drugs and 13 different subgroups of birth defects.
However, Pasternak and Hviid stressed that the number of exposed
cases in each subgroup was small.
"Genital herpes is a common sexually transmitted disease in women of reproductive age. Its prevalence in women is actually higher than in men," noted Dr. Jennifer Wu, an obstetrician/gynecologist at Lenox Hill Hospital in New York City. She called the findings "reassuring for patients who may need to use the medications in the first trimester."
Dr. James L. Mills, an investigator in the Epidemiology Branch
of the Eunice Kennedy Shriver National Institute of Child Health
and Human Development and coauthor of an accompanying journal
editorial comment that, "herpes viruses are an important problem
during pregnancy. Many women are treated but there was, until now,
only limited information regarding the possible teratogenicity
[ability to harm the fetus] of the treatment."
The Danish study answers one key question: are acyclovir and
related compounds adding significantly to the number of children
born with birth defects? "The answer is no," he said.
For more information on pregnancy, visit the
National Institutes of Health.