Microbial composition across body sites in polycystic ovary syndrome: a systematic review and meta-analysis.

Plain Language Summary

Polycystic ovary syndrome (PCOS) is a common hormonal disorder that affects women of childbearing age. The condition is marked by menstrual irregularities, excess levels of androgens (hormones usually dominant in males), and the presence of ovarian cysts. Additionally, it is linked to weight gain, and infertility, as well as an increased risk of developing diabetes and cardiovascular disease. The exact cause of PCOS remains unclear due to its complex nature. Emerging research suggests a potential connection between the microbiome and PCOS. As the human microbiome influences hormone metabolism, it has been postulated that changes in microbial composition could contribute to the development and manifestation of the condition. Yet, due to the variability in influencing factors, it has not been easy to compare studies and find clear links. Hence this review and meta-analysis sought to update current evidence regarding microbial composition in women with PCOS. It included 34 studies that had gathered data on microbial composition from the mouth, blood, gut, and reproductive tract of women with PCOS. But due to a shortage of suited studies, the meta-analyse ended up focusing primarily on the gut. Overall, women with PCOS had significantly less microbial diversity. Specifically in the gut the data indicated that certain bacteria types were increased, such as Prevotella, Shigella, and Escherichia, while beneficial bacteria like Lactobacilli and Bifidobacteria decreased. Similarly, in the vaginal microbiome, species associated with reproductive pathologies were increased, such as Gardnerella and Prevotella, and a reduction in beneficial Lactobacilli. The authors suggested that through many pathways such observed dysbiosis may contribute to the pathologies of PCOS. They stressed that while there is growing evidence linking microbial composition to PCOS, many microbiome studies lack rigorous design and consideration of other influencing factors that alter the microbiome. More well-designed research is needed.