REDUCED INCIDENCE OF PRETERM DELIVERY WITH METRONIDAZOLE AND ERYTHROMYCIN IN WOMEN WITH BACTERIAL VAGINOSIS

Background. Pregnant women with bacterial vaginosis may be at increase d risk for preterm delivery, We investigated whether treatment with me tronidazole and erythromycin during the second trimester would low er the incidence of delivery before 37 weeks' gestation. Methods. In 624 pregnant women at risk for delivering prematurely, vaginal and cervica l cultures and other laboratory tests for bacterial vaginosis were per formed at a mean of 22.9 weeks' gestation. We then performed a 2:1 dou ble-blind randomization to treatment with metronidazole and erythromyc in (433 women) or placebo (191 women). After treatment, the vaginal an d cervical tests were repeated and a second course of treatment was gi ven to women who had bacterial vaginosis at that time (a mean of 27.6 weeks' gestation). Results. A total of 178 women (29 percent) delivere d infants at less than 37 weeks' gestation. Eight women were lost to f ollow-up, In the remaining population, 110 of the 426 women assigned t o metronidazole and erythromycin (26 percent) delivered prematurely, a s compared with 68 of the 190 assigned to placebo (36 percent, P = 0.0 1). However, the association between the study treatment and lower rat es of prematurity was observed only among the 258 women who had bacter ial vaginosis (rate of preterm delivery, 31 percent with treatment vs. 49 percent with placebo; P = 0.006). Of the 358 women who did not hav e bacterial vaginosis when initially examined, 22 percent of those ass igned to metronidazole and erythromycin and 25 percent of those assign ed to placebo delivered prematurely (P = 0.55). The lower rate of pret erm delivery among the women with bacterial vaginosis who were assigne d to the study treatment was observed both in women at risk because of previous preterm delivery (preterm delivery in the treatment group, 3 9 percent; and in the placebo group, 57 percent; P = 0.02) and in wome n who weighed less than 50 kg before pregnancy (preterm delivery in th e treatment group, 14 percent; and in the placebo group, 33 percent; P = 0.04). Conclusions. Treatment with metronidazole and erythromycin r educed rates of premature delivery in women with bacterial vaginosis a nd an increased risk for preterm delivery.