Estrogen-replacement therapy has been proven to prevent bone loss and fractures in postmenopausal women. Similarly, women with a history of COC use are less likely to have low bone mineral density later in life (RR = 0.35, 95% CI 0.2–0.5).88 The effect of COCs on increasing bone mineral density appears to be related to duration of use.88 As the first large population of COC users pass into menopause, future epidemiologic studies will determine whether women with a history of COC use have fewer fractures than women who never used COCs. It also remains to be seen if a past history of COC use is protective against osteoporosis in the presence and absence of postmenopausal estrogen-replacement therapy.