Background/Aims Hormonal contraception is a popular contraceptive choice among sexually-active women. Yet, its association with body composition in younger women is not well understood. We compared body composition measures by

1. duration of Depo-Provera (DMPA) use and

2. dose and duration of oral contraceptive (OC) use in adolescent and young adult women.

Methods Study participants were Group Health Cooperative members. DMPA use (new, prevalent, or none) was collected in 170 adolescents aged 14–18 years, and in 440 women aged 18–39 years. OC use was gathered in 301 adolescents aged 14–18 years, and 305 women aged 19–30 years. Among OC users, ethinyl estradiol (EE) dose (=30mcg vs. <30mcg) and months of use were also collected. For all participants, weight, BMI, and truncal and total fat and lean mass were estimated using DEXA. Mean differences in baseline body composition by dose and duration of hormone contraception use were compared cross-sectionally using ANOVA.

Results Adolescents who were prevalent DMPA users had higher baseline truncal and total fat mass compared to adolescent non-DMPA users. For example, baseline mean (SE) total fat mass was 23.3 (1.2) kilograms for prevalent DMPA users, but was 19.9 (0.9) kilograms for non-DMPA users (p<0.05). No mean differences in the body composition measures were observed between new DMPA vs. non- DMPA adolescent users or among young women, regardless of DMPA use. With OC use, baseline BMI and truncal and total fat mass differed by EE dose in young adult women. Baseline mean (SE) total fat mass, in kilograms, for women using =30mcg EE doses, <30mcg EE doses, and for non-OC users was 20.8 (0.9), 19.0 (0.9), and 22.2 (0.9), respectively (p=0.02). No differences were noted between EE dose and body composition indices in adolescents. For both adolescents and young women, baseline body composition was not associated with duration of OC use.

Conclusions Our results suggest that DMPA use is associated with fat mass in adolescents and that EE dose in OCs is associated with fat mass in young adult women. Analysis of follow-up data to determine if these relationships continue to be seen longitudinally is needed.