Teenage girls taking low-dose oral contraceptives showed abnormally low levels of bone growth, and sometimes even lost density.
In a randomized, crossover trial, bone mineral density (BMD) failed to increase in girls 15 to 19 years old who took pills with a low dose (15 micrograms) of ethinyl estradiol. Ethinyl estradiol is a form of the female hormone estrogen that's commonly used in birth control pills.
Lumbar spine BMD and whole body bone mineral content were measured at the outset of the study and after a nine-month period.