Husain S, et al. - Via performing randomized, double-blind, placebo-controlled trial, researchers investigated how vaginal microbiota is affected when oral probiotic preparation is administered from early pregnancy. They randomly allocated women aged 16 years or older recruited at 9–14 weeks' gestation to receive oral capsules of probiotic containing Lactobacillus rhamnosus GR-1 and Lactobacillus reuteri RC-14 each at 2.5 × 10⁹ colony-forming units (CFUs) or placebo once daily from recruitment until the end of pregnancy. They included 78% (238/304) of participants who initially consented (probiotic group 123, placebo group 115) in the primary analysis. At 18–20 weeks' gestation, the groups showed no differences in the rates of bacterial vaginosis, 15% (19/123) in the probiotic group vs 9% (10/115) in the placebo group. The groups were not different regarding the proportion of women colonized with the probiotic strains, Escherichia coli, Group B streptococci or other vaginal microbiota. The alpha diversity or composition of the bacterial communities between or within the probiotic and placebo groups at 9–14 and 18–20 weeks’ gestation were also not different. These findings suggest no modifying effect of oral probiotics on the vaginal microbiota when taken from early pregnancy.