January 15, 2010 --Long-term use of low-dose versions of the birth control pill may decrease a young woman's bone density. A study in the journal Contraception found that those taking birth control pills for more than two years and those on low-dose estrogen pills appear to have the greatest risk of decreased bone density in the spine and the whole body.
What's not known is the long-term impact.
Almost 12 million women are currently using oral contraceptives. The use is highest in women under 30, a time of peak bone mass production.