The Vaginal Microbiome: Associations with Vaginal pH, Menopause and Metabolic Parameters

The vaginal microbiota, a critical determinant of women's health, is influenced by hormonal and metabolic parameters across the lifespan. While Lactobacillus species are beneficial markers of vaginal health, microbial composition undergoes pronounced alterations after menopause. This study aimed to elucidate the associations between vaginal microbiota composition, vaginal pH, menopausal status, and metabolic parameters in Asian women. Vaginal secretion samples were collected from 40 women (20 premenopausal, 20 postmenopausal). Full-length 16S rRNA gene sequencing was used to characterize the microbiota, categorized into Community State Types (CSTs): CST-I + II (Lactobacillus crispatus/gasseri, protective), CST-III (Lactobacillus iners, neutral), and CST-IV (anaerobic bacteria, harmful). Vaginal pH and clinical data were assessed in relation to microbial profiles. CST distribution differed significantly by menopausal status and vaginal pH. Harmful-type CST-IV was more prevalent in postmenopausal women (70% vs. 40%, p < 0.05), while CST-III was dominant in premenopausal women (45% vs. 5%). CST-IV was associated with elevated pH (median 6.00, p = 0.026) and increased abundance of anaerobes including Bacteroides, Fusobacterium, Porphyromonas, Prevotella, and Streptococcus. Oral antibiotic use reduced both beneficial and harmful CSTs, shifting toward neutral CST-III (75%, p = 0.048). Use of sodium-glucose cotransporter-2 (SGLT2) inhibitors in postmenopausal women was associated with a higher prevalence of protective CST-I + II (57.14% vs. 8.33%, p < 0.05), though no significant impact on pathogen presence was observed. This study highlights the dynamic interplay between menopausal status, metabolic interventions, and vaginal microbiota composition. Findings may inform targeted strategies to maintain vaginal health in aging populations.