It's the latest entry on a subject that has generated controversy: to treat or not to treat. The British researchers, writing in the March 22 issue of The Lancet, acknowledge that at least two other studies have gotten negative results. However, "the type, dose and route of antibiotic used might be important with respect to outcome," the group at St. George's Hospital in London writes.
They screened 6,102 women making their first prenatal hospital visit, at anywhere from 12 to 22 weeks of pregnancy. They picked out 494 women with symptom-free vaginal infections and divided them into two groups. One got twice-daily, 300-milligram oral doses of the antibiotic clindamycin, the other got a placebo, an inactive substance.
A few women dropped out of the study, but the clinical results were clear, the researchers write: "Women receiving clindamycin had significantly fewer miscarriages or preterm deliveries" -- 13 of 244 in the antibiotic group, 38 of 241 in the placebo group.
The benefits were especially great for women with severe infections. The incidence of miscarriage and preterm delivery was 5.4 percent for those who got the antibiotic, 35.7 percent for those who didn't.
It's a result that pushes obstetricians and gynecologists further toward antibiotic treatment when an infection is found, says Dr. Samuel Bender, a clinical assistant professor of obstetrics and gynecology at New York University School of Medicine.
"There has been a lot of literature in the last decade or so going backward and forward on it," Bender says. "Some studies show that treatment makes a difference, some show it does not." One factor involved in the mixed results is that different studies have used different antibiotics, different doses and different routes of delivery, oral or vaginal, he says. Two negative studies that got a lot of attention in the field used a different drug, metronidazole, Bender adds.
The latest study, he says, "offers a compelling reason to treat patients with antibiotics, even in the absence of symptoms."
In his own practice, Bender says, "When I have a patient with a positive culture, I tend to treat, knowing that I may be doing some good and hoping that I am not doing any harm."
As for screening, says Dr. Sandra A. Carson, a professor of obstetrics and gynecology at the Baylor School of Medicine, "it's something we do all the time by getting a Pap smear," adding the advice of the American College of Obstetrics and Gynecology that "women should have a Pap smear every year." Her assessment is that the new study "may mean that patients, even if asymptomatic, need to be treated."
More information about vaginal infections is available from the National Women's Health Information Center and the National Institute of Allergy and Infectious Diseases.