A randomised controlled trial of vaginal clindamycin for early pregnancy bacterial vaginosis

To determine whether treatment of bacterial vaginosis (BV) with vaginal clindamycin affects pregnancy outcome.

Mothers with singleton pregnancies and without previous preterm delivery in 17 health centres in Oulu from March 1996 Until March 1998, in whom BV was diagnosed by Gram stain of a vaginal swab at the first antenatal visit (at the 12th gestational week) were randomised at Oulu University Hospital to have a one-week course of vaginal clindamycin, or placebo. A follow up sample of Gram stain was taken two weeks after randomisation and at the 30th gestational weeks. Pregnancy outcome data was obtained from hospital records. Primary outcome was preterm birth, and puerperal infectious morbidity the other outcome measure.

During the study period 1956 women were screened, of whom 143 (7.3%) were BV- positive. One hundred and one were randomised. The total preterm birth rate of BV+ women randomised was 9.9% (10/101). Preterm birth occurred in 20.7% (6/29) vs 0% (0/26) according to whether BV persisted or not (P < 0.01). The preterm birth rate was 13.7% (7/51) in the clindamycin group vs 6.0% (3/50) in the placebo group (OR 2.5, 95% CI 0.6-10). BV was cured just after treatment in 17 out of 51 (33%) of the clindamycin- treated patients vs 17 out of 50 (34%) of the placebo- treated patients (OR 1.0, 95% CI 0.4-2.2). There was a difference in puerperal infectious morbidity in patients where BV persisted (31%, 9/29) compared with those in which BV did not persist (7.7%, 1/26) (OR 5.4, 95% CI 1.04-28). Infections were seen in 4/51 (8%) of the clindamycin treated vs 10/50 (20%) of the placebo treated cases, (OR 0.3, 95% CI 0.1-1.2).

The prevalence of BV was lower than expected in this low risk population, but nevertheless it increased the risk of preterm birth and puerperal infectious morbidity, the risk being highest in cases where BV persisted during pregnancy. Vaginal clindamycin treatment for BV in the first trimester of pregnancy did not appear to reduce the risk of preterm birth or puerperal infections.