The study, led by J. Christopher Carey, M.D., then of the University of Oklahoma, in Oklahoma City, appears in the February 24 New England Journal of Medicine .
Researchers are unsure of how the condition is transmitted.
Bacterial vaginosis affects about 800,000 pregnant women each year in the U.S., and women with the condition are more likely than are other women to give birth prematurely, he added. Similarly, the 4,000 deaths that result from premature birth, as well as the 4,000 cases of damage to the nervous system, could also be prevented. For the study, the researchers treated 953 pregnant women with the antibiotic metronidazole, and 966 women with a placebo. The women received their first treatment between their 16th and 23rd weeks of pregnancy, and their second treatment between their 24th and 29th weeks of pregnancy. Bacterial vaginosis was eliminated in about 77 percent of the women who received the antibiotic, and about 37 percent of the women who received the placebo.