The vaginal microbiome composition of premenopausal and postmenopausal women: A systematic review

Abstract

Introduction: The vaginal microbiome is a critical modulator of vaginal immunology and undergoes constant changes throughout life. While the vaginal microbiota of premenopausal women is extensively studied, its composition and implications on vaginal health in peri-menopausal and postmenopausal women remains unclear. Notably, differences in vaginal microbiome composition may influence susceptibility to mucosal infections, including bacterial vaginosis (BV), sexually transmitted infections (STIs), and human immunodeficiency virus (HIV).

Methods: With no time restrictions, a systematic search of Ovid EMBASE and Ovid Medline was conducted from inception to May 2024. Three independent reviewers screened titles, abstracts, and full texts and extracted data on population demographics, sequencing methods, BV diagnostic criteria, and vaginal microbiome composition. The inclusion criteria were studies comparing premenopausal and postmenopausal women with outcomes reporting vaginal bacterial composition. Secondary outcomes include hormone or estrogen levels and glycogen content.

Results: Five studies met the inclusion criteria. These studies span two countries, with participants aged 18 to 61 years. Four studies used 16S rRNA gene sequencing; one used bacteria-specific qPCR. Premenopausal women predominantly exhibited Lactobacillus-dominated community state types (CSTs) I and III, with higher glycogen levels and lower vaginal pH compared to postmenopausal women. The vaginal microbiomes of postmenopausal women are largely presented as CST-IV, characterized by reduced Lactobacillus spp. and increased diversity of other anaerobes. Estrogen therapy partially restored Lactobacillus dominance, improving microbial stability. Transition rates between CSTs were more frequent in premenopausal women, typically between Lactobacillus crispatus-dominant (CST I) and high-diversity anaerobic-dominant (CST IV).

Discussion: Age-related changes in the vaginal microbiome underscore the impact of hormonal decline and glycogen availability on microbial dynamics. The differences in vaginal microbiome composition access life stages may reflect age-related susceptibility to urogenital conditions. Estrogen therapy emerges as a potential intervention to restore microbial balance and improve vaginal health outcomes in postmenopausal women.

Conclusion: Further research is needed to explore targeted interventions supporting microbial resilience across life stages. Such interventions could inform strategies to prevent urogenital conditions and enhance overall vaginal health for women as they age.