The Relationship Between 2D:4D Digit Ratio and Polycystic Ovary Syndrome: A Systematic Review

This systematic review aimed to synthesize current evidence on the association between 2D:4D ratios and PCOS.

A comprehensive literature search was performed in PubMed, Web of Science, Scopus, and Cochrane Library databases between May and June 2025. Two independent researchers conducted study screening, data extraction, and quality appraisal using the Joanna Briggs Institute critical appraisal tools.

Eleven studies published between 2005 and 2024, with sample sizes ranging from 40 to 400 participants, were included. Study designs were cross-sectional or case-control, and measurement techniques involved calipers, photocopies, or digital analysis. Nine studies reported significantly lower 2D:4D ratios in women with PCOS compared to healthy controls, supporting the hypothesis of increased prenatal androgen exposure. However, two studies found no significant association, likely due to methodological heterogeneity, small sample sizes, or diagnostic inconsistencies.

The majority of included studies suggest that lower 2D:4D ratios may reflect elevated prenatal androgen exposure in women with PCOS, indicating its potential as a non-invasive biomarker. Nonetheless, variability in diagnostic criteria, measurement methods, and study populations limits generalizability. Further large-scale, standardized research is required to determine clinical utility and to establish population-specific reference values.