Vaginal lactobacilli, probiotics, and IVF.

Perturbation of the normal lactobacilli-dominated vaginal microflora is associated with reproductive failure and adverse pregnancy outcomes, ranging from early pregnancy loss to late miscarriage and preterm birth. As high rates of bacterial vaginosis are observed with IVF patients, abnormal vaginal microflora presumably explain, at least to some extent, reproductive failure as well as the increased risk of adverse pregnancy outcome seen in these patients. Accordingly, there may be a window of opportunity for improving IVF success rates and outcomes. At present, a screen-and-treat procedure to restore the normal vaginal microflora is not a routine part of the infertility work-up and treatment. While Gram staining of vaginal smears would offer an inexpensive and validated means for screening and diagnosis, probiotics that contain live lactobacilli capable of re-colonizing the vagina may offer an elegant and safe choice of treatment. Carefully designed trials using well characterized probiotic strains and treatment regimens are still required to evaluate the effect of probiotics on IVF-embryo transfer pregnancy rates.