beta diversity in the gut microbiota of women with polycystic ovary syndrome: a systematic review and meta-regression analysis

Polycystic ovary syndrome (pcos) is a common endocrine disorder with both metabolic and reproductive complications. emerging evidence suggests that gut microbiota dysbiosis may contribute to pcos pathogenesis via low-grade inflammation, insulin resistance, and hormonal imbalance. however, findings on microbial beta diversity remain inconsistent. this study systematically evaluated beta diversity differences in the gut microbiota of women with pcos and explored factors influencing statistical significance. a systematic review and meta-regression were conducted following prisma guidelines. pubmed, scopus, and web of science were searched for english-language articles published up to march 2024. eligible studies assessed beta diversity using bray-curtis, unifrac, or the jaccard index. study quality was appraised using the newcastle-ottawa scale (nos). heterogeneity was modeled with a generalized linear mixed model (glmm), and effect estimates were reported as odds ratios (or) with 95% confidence intervals. among 27 eligible studies, 15 reported significant gut microbial differences between pcos and controls, while 12 did not. meta-regression showed no significant predictors (p > 0.1). studies using non-standard beta diversity methods were less likely to report significant results (or = 0.165, p = 0.178). most studies were of moderate to high quality (nos ≥ 6). findings suggest that heterogeneity in beta diversity results largely reflects methodological inconsistencies. standardization in microbiota analysis—particularly beta diversity metrics—is essential for reproducibility. future research should employ unified pipelines, functional profiling, and longitudinal designs to clarify the gut microbiota’s role in pcos pathogenesis.