Evidence from a Cochrane systematic review (10 randomized controlled trials [RCTs]) indicates that both oral and intravaginal antibiotics are effective at eradicating bacterial vaginosis (BV) in pregnant women. Although there was no direct comparison, oral antibiotics appeared to have similar efficacy to intravaginal antibiotics, and clindamycin (oral or intravaginal) appeared to have similar efficacy to other antibiotic treatments.

A Cochrane systematic review (search date: to May 2006) considered the use of antibiotics to treat BV in pregnancy [McDonald et al, 2007]. The review included 15 RCTs of good quality (n = 5888); 10 RCTs (n = 4357) reported results for eradication of BV:

• Antibiotic treatment (any regimen) was significantly more effective at eradicating BV than placebo or no treatment. In the antibiotic treatment group, 488 of 2214 women (22%) tested positive for BV after treatment, compared with 1347 of 2143 women (63%) in the placebo/no treatment group (odds ratio [OR] for failure of test of cure 0.17, 95% CI 0.15 to 0.20). There was significant heterogeneity among trials in this comparison, but using random-effects analysis made little difference to the result.
• The route of administration did not appear to make a difference to the effect of the antibiotic:
• Oral antibiotics compared with placebo or no treatment (seven trials, n = 3244): OR 0.15, 95% CI 0.13 to 0.17.
• Intravaginal antibiotics compared with placebo or no treatment (three trials, n = 1113): OR 0.27, 95% CI 0.21 to 0.35.
• Data from four trials (n = 1575) comparing clindamycin (oral or intravaginal) were pooled separately:
• Clindamycin was significantly more effective than placebo or no treatment at eradicating BV.
• In the clindamycin group, 141 of 785 women (18%) tested positive for BV after treatment, compared with 495 of 790 women (63%) in the placebo/no treatment group (OR 0.14, 95% CI 0.12 to 0.18).