Fourteen RCTs (n=6,728) were included.
Antibiotics for bacterial vaginosis.
Eradication of bacterial vaginosis (5 RCTs): Antibiotics significantly reduced the risk of persistent bacterial vaginosis (RR 0.32, 95% CI: 0.20, 0.52, P<0.001).
Pre-term birth before 37 weeks (11 RCTs): there was no statistically significant difference between the groups treated with antibiotics versus no antibiotics (RR 0.93, 95% CI: 0.70, 1.22, P=0.6). Statistically significant heterogeneity was detected (P<0.001). The results were similar for pre-term delivery before 35, 34, 32 and 28 weeks. There were no statistically significant differences between the groups treated with antibiotics versus no antibiotics for high-risk women (RR 0.75, 95% CI: 0.45, 1.24, P=0.30). Statistically significant heterogeneity was detected (P=0.001). There was also no statistically significant difference between metronidazole and no antibiotics for all women (RR 1.08, 95% CI: 0.73, 1.59, P=0.70). Statistically significant heterogeneity was detected (P=0.002).
Antibiotics for Trichomonas vaginalis.
Eradication of Trichomonas vaginalis (3 RCTs, 2 included in meta-analysis): antibiotics significantly reduced the risk of persistent Trichomonas vaginalis (RR 0.18, 95% CI: 0.07, 0.48, P<0.001).
Pre-term birth (1 RCT): the RCT found that, compared with no antibiotic, treatment with metronidazole was associated with an increased risk of pre-term delivery before 37 weeks for all women (RR 1.78, 95% CI: 1.19, 2.66, P=0.005) and for women at high risk (RR 1.84, 95% CI: 1.07, 3.18, P=0.03). The RCT found no statistically significant difference between treatments for pre-term delivery before 35 weeks for all women (the results were reported).