ObjectivesTo systematically review the efficacy of living preparation of lactobacillus for bacterial vaginosis (BV) during pregnancy.MethodsPubMed, Web of Science, Medline (OVID), CNKI, WanFang Data, VIP and CBM databases were electronically searched to collect randomized controlled trials (RCTs) of living preparation of lactobacillus for BV during pregnancy from inception to September 30th, 2019. Two reviewers independently screened literature, extracted data and assessed risk of bias of included studies, then, meta-analysis was performed by RevMan 5.3 software.ResultsA total of 21 RCTs involving 2 930 patients were included. The results of meta-analysis indicated that: living preparation of lactobacillus was superior to metronidazole in effective rate (RR=1.05, 95%CI 1.02 to 1.07, P=0.000 4), premature delivery rate (RR=0.49, 95%CI 0.32 to 0.73, P=0.000 4), premature rupture of membrane rate (RR=0.54, 95%CI 0.38 to 0.77, P=0.000 7), infant of low-birth weight rate (RR=0.45, 95%CI 0.22 to 0.94, P=0.03) and puerperal infection rate (RR=0.60, 95%CI 0.39 to 0.94, P=0.03).ConclusionsThe current evidence shows that, living preparation of lactobacillus is superior to metronidazole for BV during pregnancy, and the incidence of adverse pregnancy outcomes (preterm delivery, premature rupture of membranes, low birth weight, puerperal infection) after treatment is lower. Due to limited quality and quantity of the included studies, more high-quality studies are required to verify above conclusions.