Context: Oral contraceptive (OC) use is common, but bone changes associated with use of contemporary OC remain unclear. Objective: The objective of the study was to compare bone mineral density (BMD) change in adolescent and young adultOCusers and discontinuers of two estrogen doses, relative to nonusers. Design and Setting: This was a prospective cohort study, Group Health Cooperative. Participants: Participants included 606 women aged 14-30 yr (50% adolescents aged 14-18 yr): 389 OC users [62% 30-35 μg ethinyl estradiol (EE)] and 217 age-similar nonusers; there were 172 OC discontinuers. The 24-month retention was 78%. Main Outcome Measure: The main outcome measure was BMD measured at 6-month intervals for 24-36 months. Results:After 24 months, adolescents using 30-35 μg EE OCs, but not those using lower-dose OCs, had significantly smaller adjusted mean percentage BMD gains than nonusers at the spine [group means (95% confidence interval for between group differences) 1.32 vs. 2.26% (-1.89, -0.13%)] and whole body [1.45 vs. 2.03% (-1.29%, -0.13%)]. Adolescents who discontinued 30-35 μg EE OC showed significantly smaller gains than nonusers at the spine after 12 months [0.51 vs. 1.72% (-2.38%, -0.30%)]. Young adult OC users did not differ from nonusers. However, OC discontinuers of both doses differed significantly from nonusers at the spine 12 months after discontinuation [-1.32%<30 μg EE, -0.92% 30-35 μg EE vs. +0.27% nonusers (-2.48, -0.54, and -1.94%, -0.55%, respectively)]. Results were similar for mean absolute BMD change (grams per square centimeter). Conclusions: Both OC use and discontinuation were associated with BMD losses/smaller gains relative to nonusers (differences < 2% after 12-24 months for all skeletal sites). The clinical significance of these results regarding future fracture risk is unknown. Study of longer-term trends after discontinuation is needed.
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism
- Clinical Biochemistry
- Biochemistry, medical