March 8, 2006

Birth defects from mom’s West Nile infection rare

By Will Boggs, MD

NEW YORK (Reuters Health) - Birth defects appear to be
uncommon in infants born to women infected with West Nile virus
(WNV) during pregnancy, according to a new report.

"The current study's findings are overall reassuring in
that the majority of the women for whom there was information
delivered apparently healthy infants with normal growth and
development," Dr. Daniel R. O'Leary from Centers for Disease
Control and Prevention, Fort Collins, Colorado told Reuters

O'Leary and colleagues studied 77 pregnant women with WNV
illness. Twenty-five women were believed to have been infected
during the first trimester, 27 in the second trimester, and 24
in the third trimester. Time of infection was unknown for 1

Four women had spontaneous abortions, two had elective
abortions, and the other 71 women delivered 72 live infants,
including one set of twins.

The frequency of spontaneous abortion, preterm delivery,
and delivery of low birthweight infants was no higher in this
group than expected in the general population, the authors

Seven infants had major birth defects, the results
indicate, but only three of these defects could have been
caused by maternal WNV infection, based on the timing of the
infections and the sensitive developmental period for the
specific malformations.

In none of the infants with major malformations could
researchers find any conclusive evidence that West Nile virus
played a role.

"The current study was conducted in follow-up to the first
documented case in 2002 of human congenital WNV infection in an
infant with severe neurologic birth defects," O'Leary
explained. Because no new cases of congenital WNV infection
were confirmed, "the 2002 report is still the only documented
congenitally acquired WNV case to date."

SOURCE: Pediatrics March 2006.