Hormonal contraception and bone metabolism: a systematic review

Abstract

Background: Although a large amount of studies in the literature evaluated the effects of hormonal contraception on bone, many questions remained still unclear, such as the effect of these therapies on fracture risk.

Study design: We performed a systematic search of the published studies from January 1975 through January 2012 on the effects of hormonal contraceptives on bone metabolism. We analyzed the overall effect on bone mineral density (BMD) and on fracture risk of combined oral contraceptives (COCs), progestogen-only contraceptives, transdermal contraceptives and vaginal ring.

Results: COC therapy does not seem to exert any significant effect on BMD in the general population. In adolescents, the effects of COCs on BMD seem to be mainly determined by estrogen dose. The use of COCs in perimenopausal women seems to reduce bone demineralization and may significantly increase BMD even at a 20-mcg dose. Use of depot medroxyprogesterone acetate is associated with a decrease in BMD, although this decrease seems to be partially reversible after discontinuation. Data on other progestogen-only contraceptives, transdermal patch and vaginal ring are still limited, although it seems that these contraceptive methods do not exert any influence on BMD.

Conclusions: Hormonal contraceptives do not seem to exert any significant effect on bone in the general population. However, other randomized controlled trials are needed to evaluate the effects on fracture risk since the data available are derived from studies having the effects on BMD as the primary end point, and BMD may not accurately reflect the real fracture risk.