Explaining recent declines in adolescent pregnancy in the United States: the contribution of abstinence and improved contraceptive use.

OBJECTIVES We explored the relative contributions of declining sexual activity and improved contraceptive use to the recent decline in adolescent pregnancy rates in the United States. METHODS We used data from 1995 and 2002 for women 15 to 19 years of age to develop 2 indexes: the contraceptive risk index, summarizing the overall effectiveness of contraceptive use among sexually active adolescents (including nonuse), and the overall pregnancy risk index, calculated according to the contraceptive risk index score and the percentage of individuals reporting sexual activity. RESULTS The contraceptive risk index declined 34% overall and 46% among adolescents aged 15 to 17 years. Improvements in contraceptive use included increases in the use of condoms, birth control pills, withdrawal, and multiple methods and a decline in nonuse. The overall pregnancy risk index declined 38%, with 86% of the decline attributable to improved contraceptive use. Among adolescents aged 15 to 17 years, 77% of the decline in pregnancy risk was attributable to improved contraceptive use. CONCLUSIONS The decline in US adolescent pregnancy rates appears to be following the patterns observed in other developed countries, where improved contraceptive use has been the primary determinant of declining rates.