By Will Boggs, MD
NEW YORK, Feb 23 (Reuters Health) -- Antibiotics do not appear to prevent
preterm birth in women who have bacterial vaginosis, a chronic vaginal
inflammation caused by an overgrowth of bacteria.
Bacterial vaginosis affects about 800,000 pregnant women annually in the
US and such women are at greater risk of preterm birth. Past studies had
indicated that antibiotic treatment might reduce the chance of preterm delivery
in women who had given birth prematurely in the past,
However, the new study found that antibiotic treatment had no effect on
early delivery, infant birthweight, or complications of pregnancy or delivery,
even though the treatment eliminated bacterial vaginosis in nearly 80% of women,
according to a report in the February 24th issue of The New England Journal of
Medicine.
"We had expected that treating bacterial vaginosis would reduce the rate
of preterm birth, but unfortunately it had no effect," Dr. Mark Klebanoff, one
of the co-authors, from the National Institute of Child Health and Human
Development (NICHD) in Bethesda, Maryland told Reuters Health.
In the study, Dr. J. Christopher Carey from University of Oklahoma in
Oklahoma City and colleagues in the NICHD Network of Maternal-Fetal Medicine
Units randomly assigned nearly 2,000 pregnant women with bacterial vaginosis to
receive oral doses of either an inactive placebo or the antibiotic
metronidazole.
About 12% of women in both groups gave birth before 37 weeks of pregnancy
(a full term pregnancy is 40 weeks). Twenty-two percent of antibiotic-treated
women experienced side effects -- primarily stomach problems, such as vomiting
-- compared with only 9% of women given a placebo.
Overall, the "results of our study do not support the use of metronidazole
to prevent preterm delivery among pregnant women with asymptomatic bacterial
vaginosis," the authors conclude, "regardless of whether they are otherwise
considered at either high or low risk for preterm delivery."
However, Dr. Ronnie Lamont from Northwick Park and St. Mark's Hospital in
London, UK disagrees with the study's conclusion.
There "is enough evidence of benefit" from antibiotic treatment that women
at high risk should be screened and treated for bacterial vaginosis, he writes
in an editorial accompanying the study.
Klebanoff notes that some guidelines do not specifically recommend
antibiotic treatment of bacterial vaginosis. The Centers for Disease Control and
Prevention's 1998 Guidelines for Treatment of Sexually Transmitted Disease, say
that a test for bacterial vaginosis can be conducted early in the second
trimester for patients who are at high risk for preterm labor. However, the
guidelines also say that current evidence does not support universal testing for
bacterial vaginosis, he notes.
