Background Many competitive women athletes experience menstrual irregularities. Athletes may also experience hidden abnormalities such as shortened luteal phase, and anovulatory cycles.
Menstrual irregularities reflect low serum estrogen levels.
Estrogen is a key hormone in bone deposition and maintenance. Women athletes with menstrual irregularities are at increased risk for low bone mass and stress fractures. Oral contraceptives contain estrogen and regulate the menstrual cycle. It is unknown if estrogen replacement prevents bone loss in women athletes with menstrual irregularities, as the hypothesis has never been tested. The study will test the hypothesis that oral contraceptives reduce stress fracture incidence and prevent loss of bone mass or increase bone mass among highly trained female athletes.