Hormone contraceptives have been related to bone changes in women. Whether such changes lead to more bone fractures later in life is not clear. However, bone health is a major public health concern. Bone density declines with age, and the change increases the risk of fracture. Due to concern about bone health, health care providers may not suggest hormone contraceptives and women may not want to use them.
We did a computer search for studies of birth control methods containing hormones and risk of fractures. Outcomes could also be bone mineral density or markers of bone changes. Birth control pills included types with both estrogen and progestin. Also included were implants and injectables with only progestin. We wrote to researchers to find other trials. We included randomized trials in any language that had at least three treatment cycles. The studies had to compare two types of birth control or one type of birth control or a supplement with a placebo or 'dummy' method.
We found 16 trials. Thirteen studies compared one birth control method with another hormone method. Two trials used a placebo or 'dummy.' One compared a hormone method to a method without hormones. None had fractures as an outcome but most looked at bone density. Birth control methods with both estrogen and progestin did not appear to affect bone health. However, 'depo,' which is injected and has only progestin, was related to lower bone density. The two trials with placebos showed increased bone density when some estrogen was given to women on depo. Bone density decreased in women who got a 'dummy' with the depo. Whether this decrease is important to the woman's health is not known. For implants, an etonogestrel implant with one rod showed a greater decrease in bone density than a two-rod levonorgestrel implant. However, other implants studied did not show the same pattern.
Whether hormone contraceptives affect fracture risk cannot be judged from current data. Hormone contraceptives work well for birth control. Health-care providers and women should think about the costs and benefits. For instance, injectable use can occur without a partner's knowledge, and is simpler than taking pills daily. Also, progestin-only methods are suggested for some women with health problems who should avoid estrogen.