Gut dysbiosis in gynecological diseases associated with female infertility: a scoping review
This scoping review maps associations between gut dysbiosis and PCOS/PMOS, endometriosis, and uterine fibroids, but establishes neither causality nor quantifiable effect magnitude for any outcome.
| Population | Women with PCOS/PMOS, endometriosis, or uterine fibroids |
|---|---|
| Intervention | Characterization of gut microbiota composition (dysbiosis profile) |
| Comparator | Women without these conditions (where available in included primary studies) |
| Outcome | Gut microbial diversity in PCOS/PMOS; Firmicutes/Bacteroidetes ratio in PCOS/PMOS; Pro-inflammatory microbiota profile in endometriosis; Gut dysbiosis in uterine fibroids; Pregnancy rate / live birth rate |
Summary of findings
| Outcome | Effect | 95% CI | Certainty | Clinical relevance | Notes |
|---|---|---|---|---|---|
| Gut microbial diversity in PCOS/PMOS | no pooled estimate; qualitative direction only: reduced alpha-diversity reported in primary studies | — | Very low | — | |
| Firmicutes/Bacteroidetes ratio in PCOS/PMOS | no pooled estimate; directional data not quantified across included studies | — | Very low | — | |
| Pro-inflammatory microbiota profile in endometriosis | no pooled estimate; qualitative association reported without effect size | — | Very low | — | |
| Gut dysbiosis in uterine fibroids | no pooled estimate; evidence described as sparse and insufficient for any directional conclusion | — | Very low | — | |
| Pregnancy rate / live birth rate | not measured in this review; in the data available | — | Very low | — |
Context
Female infertility affects approximately 186 million people worldwide; PCOS, endometriosis, and fibroids account for a substantial proportion of cases. The hypothesis that gut microbiota alterations modulate the hypothalamic-pituitary-ovarian axis and systemic inflammation drives growing scientific output. Scoping reviews are mapping instruments, not tools for quantitative synthesis, and their results do not support direct clinical recommendations.
What the study showed
The review identifies qualitative associations between gut dysbiosis and the three gynecological conditions evaluated, without providing pooled effect estimates, 95% CIs, or absolute numbers. In PCOS, included primary studies report reduced microbial diversity and alterations in Firmicutes/Bacteroidetes ratios; in endometriosis, pro-inflammatory microbiota patterns; in fibroids, evidence is sparse. No fertility outcome (pregnancy rate, live birth rate) was directly measured by the review. Absence of meta-analysis prevents any effect quantification.
How it was done
Scoping review conducted per PRISMA-ScR; searches in PubMed, Scopus, and Google Scholar up to November 2025; English-language publications from 2015 to 2025; no prior protocol registration; no formal risk-of-bias assessment of included studies; exclusion of case reports, conference abstracts, and animal/in vitro studies without direct relevance.
Effect magnitude
No effect measure (RR, OR, SMD, MD) was calculated. The review is descriptive and qualitative; the magnitude of association between gut dysbiosis and female infertility remains undetermined.
Risk of bias
No formal risk-of-bias assessment was performed (tools such as RoB 2, ROBINS-I, or AMSTAR-2 were not applied), a methodological limitation explicitly acknowledged by the authors. The protocol was not prospectively registered, increasing the risk of selective reporting bias. Heterogeneity in microbiota analysis methods across primary studies (different sequencing platforms, 16S rRNA regions, variable diagnostic criteria) prevents direct cross-study comparison. Gray literature was explicitly excluded, potentially amplifying publication bias.
What this study does NOT prove
This review does not prove causality between gut dysbiosis and female infertility in any of the conditions evaluated. Findings are not generalizable to populations outside the samples of included primary studies, whose demographic and methodological characteristics vary widely.
In clinical practice
This review does not provide sufficient basis to alter clinical protocols. Clinicians should not use gut microbiota profiling as a diagnostic or prognostic biomarker for infertility associated with PCOS, endometriosis, or fibroids based on this document. Microbiota-targeted interventions (probiotics, dietary modifications) to improve fertility in these conditions lack supporting RCT evidence with primary reproductive outcomes.
Limitations
No formal risk-of-bias assessment was performed (tools such as RoB 2, ROBINS-I, or AMSTAR-2 were not applied), a methodological limitation explicitly acknowledged by the authors. The protocol was not prospectively registered, increasing the risk of selective reporting bias. Heterogeneity in microbiota analysis methods across primary studies (different sequencing platforms, 16S rRNA regions, variable diagnostic criteria) prevents direct cross-study comparison. Gray literature was explicitly excluded, potentially amplifying publication bias.
What is still missing
RCTs with primary reproductive outcomes (live birth rate, clinical pregnancy rate) testing gut microbiota interventions in women with PCOS, endometriosis, or fibroids. Standardization of microbiota analysis methods and diagnostic criteria across studies is a prerequisite.
Technical appendix
Version history
- 1.0 · 2026-10-23 — Auto-generated under Evidence Standard v1.0