Multimodal profiling establishes ovarian fibrosis as a measurable and targetable hallmark of human reproductive aging

Ovarian aging underpins infertility, systemic morbidity, and mortality in women. Stromal fibrosis is implicated in ovarian aging but has not been defined in the human ovary in situ. We integrated shear wave elastography (SWE), extracellular matrix (ECM) neoepitope fingerprinting, and single-cell RNA sequencing of follicular fluid aspirates within the same individual to comprehensively profile ovarian fibrosis. In an age-stratified cohort (≤33 and ≥37 years; N=32), age predicted ovarian stiffness, while mean stiffness was independently associated with reduced oocyte yield and follicular efficiency. ECM profiling revealed a dynamic fibrotic index favoring formation over degradation products. Single-cell transcriptomics demonstrated an age-associated fibroinflammatory stromal program enriched in pro-fibrotic pathways with stromal-immune crosstalk. In a larger validation cohort (25-45 years; N=100), age was similarly associated with ovarian stiffness. Thus, ovarian fibrosis is a quantifiable hallmark of human reproductive aging and represents a robust potential non-invasive biomarker and target for therapeutic intervention.