Age of pubertal onset and 2nd to 4th digit ratios: Preliminary findings

The second to fourth digit ratio (2D:4D) is used as a marker of prenatal sex hormone exposure. The aim of this study was to evaluate the possible relation between digit ratio and age of pubertal onset.

Participants were 321 men and 202 women aged between 18 and 28 at the time of assessment who self-reported their onset of puberty (i.e., age at first conscious ejaculation or menarche). Participants' right and left digit lengths were measured from hand scans.

All groups of males, i.e., early, average, and late pubertal onset, had lower mean 2D:4D than the comparable female groups, regardless of the relative timing of their pubertal onset. Among the males, there was a significant difference in digit ratios between individuals who experienced early, average, and late onset of puberty. In the males, we observed a positive relationship between 2D:4D and age of pubertal onset for both right and left hands. There were no significant differences in 2D:4D among the three groups of female maturers. We observed no significant association between digit ratios and age at menarche.

These data lend further support for using 2D:4D as a measure of prenatal androgen exposure.