For women who use the shot (a.k.a. Depo-Provera), there's good news and there's weird news. For years women have been warned that the shot can cause loss of minerals in their bones—which could mean they're more prone to bone fractures. A new study from England found that women using the shot did have a higher risk of broken bones compared to women using other types of birth control—but that was the case before they ever used the shot.
Yep, you read that right. The study found that:
Women who eventually used the shot were 30% more likely to have a broken bone before starting the method compared to women who went on to use a different birth control method.
After starting the shot, women were no more likely to have a broken bone than before.
Women who used the shot for more than two years were no more likely to have a broken bone than women who used the shot for less time.
It's true that the shot may temporarily decrease bone mineral density while a woman is using it—though research has shown that the minerals come back after a woman stops using it. What this study suggests is that the temporary decrease in bone minerals doesn't mean more broken a bones in the long run.
Maybe you're wondering, if this is true, why the label for Depo carries a warning about its effect on bone density. Unfortunately, a lot goes into updating labels, so they don't always reflect the latest research.
Why are women who use the shot more likely to break a bone?
Unfortunately, this study can't tell us much about how women who chose the shot were different from women who chose other methods. The researchers could only use information on medical charts kept by health care providers, which don't necessarily include detail about other risk factors for broken bones such as playing sports, physical inactivity, smoking, nutritional problems, or a family history of broken bones. The good news is that regardless of what birth control method you use, exercising and eating right can go a long way toward keeping your bones strong.