The effect of hormone therapy on vaginal microbiota in women with genitourinary syndrome of menopause: A double-blind, randomized, placebo-controlled trial.

This double-blind, randomized, placebo-controlled trial investigated the effects of oral combined menopausal hormone therapy (MHT) on vaginal microbiota and clinical outcomes in postmenopausal women with genitourinary syndrome of menopause (GSM). Thirty-four healthy postmenopausal women aged 40-60 years with moderate to severe GSM were randomized to receive either oral estradiol 1 mg/dydrogesterone 5 mg (Femoston conti®) or placebo daily for 12 weeks. Vaginal microbiota was assessed at baseline and week 12 using 16S rDNA gene sequencing. Clinical outcomes, including the most bothersome symptom (MBS), vaginal atrophy score (VAS), vaginal pH, vaginal health index (VHI) and vaginal maturation value (VMV), were evaluated at baseline, week 6, and week 12. The MHT group demonstrated significant more improvement in all clinical measures compared with placebo: MBS (p = 0.008), VAS (p < 0.001), vaginal pH (p = 0.001), VHI (p < 0.001) and VMV (p < 0.001). However, no significant differences were observed in microbial composition or diversity between groups after treatment. These findings suggest that while systemic hormone therapy provides meaningful symptom relief and improves vaginal tissue health, these clinical benefits can occur without concurrent, statistically significant changes in the vaginal microbiota. This supports the clinical value of early systemic MHT in managing GSM, even in the absence of microbiome restoration.