Bone mineral density in women aged 40–49 years using depot-medroxyprogesterone acetate, norethisterone enanthate or combined oral contraceptives for contraception

Abstract

Most studies show that depot-medroxyprogesterone acetate (DMPA) has a negative effect on bone mass. There are conflicting reports with respect to recovery of bone mass with long-term use of DMPA. No information is available on the effect of norethisterone enanthate (NET-EN) on bone mass, and combined oral contraceptives (COCs) have not been found to be associated with loss of bone mass. The aim of this study was to investigate bone mineral density (BMD) in older women (40–49 years) in relation to use of DMPA, NET-EN and COCs for at least 12 months preceding recruitment into the study. One-hundred twenty-seven users of DMPA, 102 NET-EN users and 106 COC users were compared to 161 nonuser controls. Bone mineral density was measured at the distal radius and midshaft of the ulna using dual X-ray absorptiometry. There was no significant difference in BMD between the four contraceptive user groups (p=.26) with and without adjustment for age. Although a small decrease in BMD was noted in the age range of 40–49 years, this was not statistically significant (p=.7). The BMD was found to be significantly associated with body mass index (BMI) (p≤.0001) at both measurement sites, with an increase of one unit of BMI translating to an increase of 0.0044 g/cm 2 in radius BMD. Follicle-stimulating hormone (FSH) level ≥25.8 mIU/mL was associated with a decrease of 0.017 g/cm 2 in radius BMD relative to women with FSH <25.8 mIU/mL. Significant interaction between FSH and BMI in their effect on BMD was observed (p=.006). This study found no evidence that long-term use of DMPA, NET-EN and COCs affects BMD in this population.