Bone mineral density in users of two kinds of once-a-month combined injectable contraceptives

C.R.T. Juliato, L. Bahamondes, M. Villarreal, B. Sobreira-Lima, J.A. Simões, A.M.S. Fernandes

Human Reproduction Unit, Department of Obstetrics and Gynaecology, School of Medicine, Universidade Estadual de Campinas (UNICAMP), Campinas, Brazil

Background The objective of this study was to compare bone mineral density (BMD) between users of two kinds of once-a-month combined injectable contraceptives (CIC) and controls.

Design and methods This cross-sectional study included 97 women of 20 to 45 years of age, using CIC containing either 25 mg of medroxyprogesterone acetate and 5 mg of oestradiol cypionate (MPA/E2Cyp) (for 12 to 82 months) or 50 mg of norethindrone oenanthate and 5 mg of oestradiol valerate (NET-EN/E2Val) (for 12 to 60 months) matched by age (± 1 year) and body mass index (BMI, kg/m2) (± 1) with users of the TCu 380A intrauterine device as controls. BMD was evaluated at the midshaft of the ulna and at the distal section of the radius of the non-dominant forearm using double X-ray absorptiometry.

Results There were no differences in BMD between users of either CIC and non-users at either section of the forearm studied. There were also no differences in BMD between users of the two CIC at either section of the forearm.

Conclusions Women aged 20 to 45 years old, currently using one of these two kinds of CIC, presented similar BMD to controls paired by age and BMI (kg/m2).

KEY WORDS  Bone mineral density, Combined injectable contraceptives, Contraception