Tightly defined inclusion criteria were making recruitment very slow.

Purpose of the study is to determine the effect of probiotic lactobacilli on the vaginal flora and cytokine profile during pregnancy, and the incidence of preterm labour in women at high risk for preterm birth.

Preterm labour involves multiple causes - one of the most significant factors being a prior history of preterm birth. Infection is another major cause of preterm labour (PTL) and is estimated to cause up to 30% of PTL. Bacterial Vaginosis (BV) is an alteration in the endogenous vaginal microflora preceded by a decreased presence of Lactobacilli species and increased growth of gardnerella and other pathogens. BV is a strong risk factor for PTL, and is associated with a 40% increased risk in some populations. Initial studies suggested that the treatment of BV with antibiotics could decrease the incidence of PTL, but this has not been confirmed by randomized trials. There is substantial evidence that the "normal" lactobacillus dominated urogenital microflora play an important role in maintenance of a healthy urinary and reproductive tract.

One hundred and sixty (160) women at high risk for PTL, based on a prior history of preterm birth, will be approached at their first antenatal visit to participate. Recruitment of 54 patients with symptomatic or asymptomatic BV (based on Nugent Scoring). Women with documented BV will be randomized to either treatment with lactobacilli preparation (n=27) or placebo (n=27). Women with symptomatic BV will be treated with oral Metronidazole prior to starting the lactobacilli or placebo. None of the subjects, researchers or clinical staff will know which preparation each woman receives.

This study will be the first to examine the ability of lactobacilli preparations to maintain a normal vaginal flora in pregnant women. In addition, the results will potentially serve as the basis for a multi-centre RCT to determine efficacy of this treatment in preventing preterm birth.

Inclusion Criteria:

• pregnant women with previous incidence of preterm labour
• otherwise healthy
• over 18 years of age
• able to provide informed consent
• less than or equal to 16 weeks gestation
• singleton pregnancy
• normal uterine cavity

Exclusion Criteria:

• significant medical complications (preeclampsia, thrombophilia, hypertension)
• multiple pregnancy
• less than 18 years of age
• patients receiving antibiotics or other antimicrobial therapies at time of recruitment
• fetal complications such as intrauterine growth restriction or other abnormalities
• diabetes
• documented need for cervical cerclage
• patient enrolled in other clinical trials