The effect of oral contraceptives on bone mass and stress fractures in female runners.

Purpose: To determine the effect of oral contraceptives (OC) on bone mass and stress fracture incidence in young female distance runners.

Methods: One hundred fifty competitive female runners ages 18-26 yr were randomly assigned to OC (30 microg of ethinyl estradiol and 0.3 mg of norgestrel) or control (no intervention) for 2 yr.