Antibiotic therapy for vaginal infections caused by bacteria (bacterial vaginosis) during pregnancy does not cut the risk of preterm birth, according to the results of a new report. This finding runs counter to the conclusions reached by three previous reports.

“Because our review is more current and we were unable to demonstrate any benefit to antibiotic treatment, even among various subgroups of women, we believe there is inadequate evidence to justify a policy of screening and antibiotic treatment of high-risk women with bacterial vaginosis to reduce the risk of preterm birth,” Dr. Nan Okun, from Mount Sinai Hospital in Toronto, and colleagues note.

The findings, which appear the journal Obstetrics and Gynecology, are based on analysis of data from 39 papers that were reviewed in detail.

Although antibiotics reduced the risk of persistent infection in women with bacterial vaginosis, the drugs had no effect on the risk of preterm birth or its associated complications. This lack of effect was observed in both high- and low-risk women.

Similarly, in women with parasitic vaginal infections (Trichomonas vaginalis) metronidazole therapy reduced the risk of persistent infection, but did not prevent preterm birth, the investigators found.

While this review suggests antibiotic treatment is not useful for preventing preterm births in women with bacterial vaginosis or Trichomonas vaginalis, the authors note that further studies, which are designed to assess relevant clinical outcomes, are justified.

SOURCE: Obstetrics and Gynecology, April 2005.