Women who were administered "birth control shot", known as depot medroxyprogesterone acetate (Depo-Provera), regularly, about 50% of them have been discovered to be suffering from weakened bones.

More than two million US ladies, and 400,000 teenagers, use depot medroxyprogesterone acetate which is injected every three months. Around 95% of these women lost at least 5 percent of their bone mineral density in the hip and lower spine within two years.

According to a study, the women who smoked and didn’t take much of calcium had seen bone loss in three years from these contraceptives.

"Bone mineral density loss is not a significant concern for all women" who use this method of birth control, said senior study author Dr. Abbey Berenson, professor in the department of obstetrics and gynecology and director of the Center for Interdisciplinary Research in Women's Health at the University of Texas Medical Branch at Galveston, in a university news release.

27 women were tracked for an year and found those who experienced significant bone mineral density loss in the first two years continued to lose bone mass.