The in vivo effect of water-based lubricants on the vaginal microbiome of women from varying age groups: exploratory analysis of a randomized controlled trial

To assess the effects of water-based lubricants on the vaginal microbiome of women from different age groups. Females from three age groups (18-29, 30-44, and 45-65 years) with mild-to-moderate vaginal dryness. Fifty females aged 18-65 were randomized to one of five lubricants (four of which were formulated to reduce their osmolality and pH). Subjects entered the study tolerance or treatment phase (vaginal intercourse minimum once a week using assigned lubricant). Four vaginal swabs per participant were sampled during pre- (baseline), post-first (2 hours, 24 hours) and post-last (4 weeks) lubricant application to assess bacterial and fungal diversity via amplicon sequencing. Vaginal pH and relative humidity were measured at baseline, 2 and 24 hours post lubricant application.Relative bacteriome abundance was statistically compared between timepoints for each treatment group. Vaginal moisture and pH were correlated with microbiome analysis. Lactobacilli and Gardnerella vaginalis were predominant across participants. Repeated lubricant application did not significantly alter vaginal microbiome for up to 4 weeks of product use (p<0.05). Microbiome diversity and abundance differed significantly between age groups. Lactobacilli was negatively associated with vaginal pH, while Gardnerella showed positive correlation with pH across all age groups. Lubricants tested showed no significant impact on the vaginal microbiome in vivo during 4 weeks; however, age and pH had significant influence between pre- and post-menopausal groups, independent of treatment.