Oral contraceptive use and bone density in adolescent and young adult women

Abstract

Background: Most of the millions of oral contraceptive (OC) users are under 30 years of age and in the critical period for bone mass accrual.

Study design: This cross-sectional study of 606 women aged 14-30 years examined both OC duration and estrogen dose and their association with bone mineral density (BMD) at the hip, spine, and whole body (dual-energy X-ray absorptiometry).

Results: Of 389 OC users and 217 nonusers enrolled, 50% were adolescents (14-18 years). Of OC users, 38% used "low-dose" OCs [<30 mcg ethinyl estradiol (EE)]. In adolescents, mean BMD differed by neither OC duration nor EE dose. However, 19- to 30-year-old women's mean BMD was lower with longer OC use for spine and whole body (p=.004 and p=.02, respectively) and lowest for >12 months of low-dose OCs for the hip, spine and whole body (p=.02, .003 and .002, respectively).

Conclusions: Prolonged use of today's OCs, particularly <30 mcg EE, may adversely impact young adult women's bone density while using these agents.

Figure 1

Mean bone density for 19–30 year-old participants, by current OC dose and duration category.^a Mean ± 95% Confidence Interval ○ Nonuser (N=110) □ 30–35 mcg, ≤12mo (N=79) Δ <30 mcg EE, ≤12mo (N=50) ■ 30–35mcg, >12mo (N=41) ▲ <30 mcg, >12mo (N=25)