Background: Women using injectable progestin contraceptives (IPCs) have lower bone mineral density than nonusers. We assessed whether bone loss is completely reversible after cessation of IPC use, whether different IPCs have different effects and whether effects vary by age at first use.
Study design: In a cross-sectional study in Cape Town, South Africa, 3487 premenopausal black and mixed race women aged 18-44 years were interviewed for information on contraceptive history and risk factors for decreased bone mineral density, and ultrasound measurements of the left calcaneus were taken. Adjusted means of the ultrasound measures for categories of IPC use were obtained using multivariable linear regression.
Results: Current users of IPCs had the lowest ultrasound measures, while the measures of women who had ceased IPC use at least 2-3 years previously were similar to or greater than those of never users of IPCs. The effects of depot medroxyprogesterone acetate and norethisterone enanthate were similar. The calcaneus measures were unrelated to age at which use began after control for confounding factors.
Conclusion: The data suggest that bone loss during IPC use is reversible and that this loss of bone is completely recovered several years after cessation of use.