Oral contraceptives, or birth control pills, are taken by
countless women in an effort to avoid unwanted pregnancy.
Bone mineral density (BMD) is a measure of how strong bones
are - and how likely
they are to break. Studies have shown an association between
these pills and changes in BMD and fracture rates. Although
most data regarding oral contraceptives suggest that they
increase BMD, few of these studies have focused on premenopausal
women who use “the pill” for birth control.
A study in the Canadian Medical Association Journal
focused on the bone densities of young women using birth control.
Over 500 women ages 25 to 45 were evaluated for oral contraceptive
use, lifestyle trends, sociodemographics, and medical histories
in the Canadian Multicentre Osteoporosis Study. Only women
who had used birth control pills for at least three months
were considered users. BMD was measured in the spine, upper
leg, and pelvis using a type of x-ray.
BMD values were lower at all measurement sites in women who
used oral contraceptives, compared to women who had never
used them. BMD was reduced 2- 4%, which may not sound like
much. Decreases in BMD this large may translate into an increased
fracture risk of 20-30%, however. Eighty-seven percent of
the women in this study had used oral contraceptives at some
point in their lives for at least three months.
If you or anyone you know is taking birth control, be aware
of all possible risks and side effects of the drugs. Talk
to your doctor of chiropractic for more information.
Prior JC, Kirkland SA, Joseph L, et al. Oral contraceptive
use and bone mineral density in premenopausal women: Cross-sectional,
population-based data from the Canadian Multicentre Osteoporosis
Study. Canadian Medical Association Journal 2001:165(8),
For additional information on women’s health, visit http://www.chiroweb.com/tyh/women.html.