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Last Updated

06 Dec 2002

Source: Reuters, March 26, 2002

Anthrax Vaccine Shows No Effect on Pregnancy Odds

By Amy Norton

NEW YORK (Reuters Health) - Anthrax vaccination does not appear to affect women's pregnancy rates, and there is no evidence that pre-pregnancy vaccination endangers pregnancy outcomes later on, according to a study of US Army personnel.

Although researchers say there is no known biological reason to believe the vaccine would have such effects, vaccine recipients have expressed concerns. The possible reproductive effects of vaccination have been the number-one concern of callers to the US Department of Defense's anthrax information line, the authors of the study point out.

More than 500,000 US military personnel have received upwards of 2 million doses of anthrax vaccine since the defense department ordered all services to begin vaccination programs in 1998.

In the new study, researchers looked at more than 4,000 women stationed at two Georgia Army bases from January 1999 to March 2000. Nearly 1,000 of these women remained unvaccinated for various reasons, such as transfer to Army posts not yet vaccinating all personnel. Pregnant women also have vaccination deferred.

The investigators found that both the vaccinated and unvaccinated women had comparable rates of pregnancy during the study period, and there was no apparent difference in outcomes such as low birth weight or birth defects.

The findings are published in the March 27th issue of The Journal of the American Medical Association.

But while the study was large enough to answer the question of effects on birth rates, it was too small to draw conclusions on any relationship between anthrax vaccination and birth outcomes, according to the lead author, Dr. Andrew R. Wiesen of the Madigan Army Medical Center in Tacoma, Washington.

"Even though we found no significant differences in birth outcomes, a well-designed larger study would be useful," he told Reuters Health.

Earlier this year, the Department of Defense released preliminary study data suggesting that anthrax vaccination during the first trimester of pregnancy might be associated with higher rates of birth defects. Military officials were advised to strengthen efforts to avoid giving the vaccine to pregnant women.

However, according to Wiesen, there is "no known biological reason" that anthrax vaccination before pregnancy would affect later pregnancy rates or outcomes.

"This study," he explained, "was conducted because of questions -- both from vaccine recipients and non-recipients -- about potential effects of the vaccine on pregnancy."

Controversy has surrounded the US military's use of the anthrax vaccine since the vaccination program began. Some 400 armed forces personnel refused vaccination because of fears that the vaccine contributed to illnesses such as those associated with Gulf War syndrome.

However, the vaccine was this month deemed largely safe by the Institute of Medicine (IOM), a scientific group that advises the federal government.

Studies of vaccinated servicemen and women have found no unexpected risk of serious illnesses after vaccination, according to the IOM committee. Skin redness and soreness at the site of injection were common, occurring in one study that found such reactions in one third to one half of all recipients. More serious reactions, including fever and malaise, were far less common.

SOURCE: The Journal of the American Medical Association 2002; 287: 1556-1560.