Low-dose oral contraceptives in adolescents: how low can you go?

The use of combined oral contraception (COC) before the accrual of peak bone mass in adolescents is common. Despite the tendency to prescribe lower ethinyl estradiol concentrations so as to reduce thromboembolic complications, concerns have developed as to whether low-dose COC provides sufficient estrogen supplementation for adequate adolescent bone development.

This paper reviews the available literature on bone mineral density (BMD) and low-dose COC in adolescents in an effort to determine whether adult-oriented recommendations for the lowest tolerated estrogen dose should apply to adolescent populations.

A MEDLINE search of all English-language literature (1966 to January 2008) was performed using the terms "adolescent," "oral contraception," and "BMD." Bibliographies were reviewed to extract additional relevant sources. Articles were selected based on pertinence to BMD changes in association with low-dose (20 microg ethinyl estradiol) hormonal contraception with emphasis on adolescent study groups.

A limited number of studies examining 20-microg preparations in adolescents have demonstrated a significantly smaller mean percentage BMD acquisition in COC groups vs untreated controls. Bone mineral density decreases appeared to positively correlate with early gynecological age of first COC use and treatment duration.

Loss of bone mass as a result of hormonal contraceptive use may have serious long-term implications in the adolescent population, who have yet to achieve peak bone density. Both age at first COC use and cumulative estrogen dose appear to be important factors in determining skeletal development in adolescents. Further studies are warranted to inform specific prescribing practices for this population.