Skip to main content

2d: 4d Digit Ratio

Meaning

The 2D:4D ratio is an anthropometric measure representing the length of the second digit (index finger) divided by the length of the fourth digit (ring finger), typically calculated from the right hand. This ratio is hypothesized to serve as a retrospective proxy biomarker for the balance of prenatal exposure to androgens, such as testosterone, versus estrogens during critical periods of fetal development. A lower ratio, where the ring finger is longer, is generally associated with higher fetal androgen exposure. Clinically, variations in this ratio are studied for their potential correlation with a spectrum of adult characteristics, including hormonal health, behavioral traits, and susceptibility to certain endocrine-related conditions.