Objectives: To compare the effect of a low-dose oral contraceptive (OC) containing 30 microg ethinyloestradiol (EE) with that of an ultra-low-dose OC containing 15 microg EE on bone turnover and BMD in healthy adolescent women and, in addition, to ascertain the influence of body mass index (BMI) and exercise on these indices of bone metabolism.
Methods: We recruited to the study 92 healthy girls aged between 16 and 19. They were divided into three groups. Participants in the first two groups used an OC with either 15 or 30 microg ethinyloestradiol (EE), whereas those in the third group used no hormonal contraception. Bone mineral density (BMD) and bone turnover markers were measured before and after 12 months of treatment.
Results: The BMD values of the total hip in females using the OC containing 30 microg EE was 0.912 g/cm(2) at baseline and 0.918 g/cm(2) after one year; in females using the OC containing 15 microg EE the corresponding values were 0.888 g/cm(2) and 0.895 g/cm(2) whereas in females who used no contraception BMD values were 0.942 g/cm(2) and 0.949 g/cm(2), respectively. The changes were statistically insignificant. Levels of osteocalcin and CTX had decreased after one year in all groups, but not statistically significantly so.
Conclusion: Low dose and ultra-low dose oral contraceptives did not significantly differ in their effects on bone mineral density or bone turnover markers in adolescent girls aged 16-19.