Determinants of Vaginal Microbiome Stability and Homeostasis

The vaginal microbiome plays a pivotal role in maintaining vaginal health and protecting the host from various diseases. There is a broad agreement within the scientific community that the vaginal microbiome exhibits stable bacterial diversity, influenced by age and gonadal hormone levels, and is classified into distinct Community-State Types. A healthy vaginal microbiome is typically characterized by a predominance of Lactobacillus spp., which acidifies the vaginal environment and is essential in defending against invading microbial pathogens. This review examines the evolution of the vaginal microbiome’s composition throughout a woman’s life. It also explores how exogenous factors influence the homeostasis of this microbiome, leading to either a state of eubiosis or dysbiosis. The main factors supporting eubiosis of the vaginal microbiome include diet, probiotic intake, certain personal hygiene practices, and hormonal contraceptives, while the major contributors to dysbiosis are psychosocial stress, tobacco smoking, and sexual activity. This state of dysbiosis is strongly associated with a range of adverse vaginal health outcomes, including preterm birth, bacterial vaginosis, pelvic inflammatory disease, and a higher risk of sexually transmitted infections.