Index-to-ring finger length ratio (2D:4D) predicts levels of salivary estradiol, but not progesterone, over the menstrual cycle.

ABSTRACT

We tested the association between the index-to-ring finger length ratio (2D4D) and ovarian steroid hormone concentrations measured over the course of a menstrual cycle in the saliva of 38 young women. Estradiol levels were positively associated with right-hand, but not left-hand, 2D4D, and also with the difference between right- and left-hand 2D4D. None of these measures predicted progesterone level.