Background:
Cross-sectional studies have demonstrated an inverse association between condom use and hormonal contraceptive use among adolescents. Further research has found that adolescents distinguish between pregnancy prevention and STD prevention.

Objective:
To prospectively examine trends in hormonal contraceptive use within individual girls relative to their condom use and pregnancy motivations.

Method:
A clinic sample of 298 African American girls aged 14 to 19 years at enrollment were interviewed every 6 months for 36 months. Girl's reported on the type of contraception and/or STD protection method used at last sex with their most recent partner. Hormone use was defined as using either oral contraceptive pills, Depo-provera, or Norplant at last sex. Girls were asked how much they wanted or did not want to get pregnant by their main partner. Hierarchical linear modeling examined trends in hormone use, condom use and desire for pregnancy using repeated measures within individuals.

Result:
Twenty percent of girls reported use of hormonal contraception at baseline compared to 10.5% at 36 months. The age-adjusted odds of an individual girl reporting hormone use at last sex declined by 2% for each six months spent in the study, averaging a 12% decline over 36 months (Odds Ratio [OR] = 0.98; 95% Confidence Interval [CI] = 0.96 – 0.99). Girls who desired pregnancy were 44% less likely to use hormonal contraception compared to girls who did not desire pregnancy (OR = 0.56; 95% CI = 0.41 – 0.77). Condom use had no statistically significant effect on hormone use trajectories.

Conclusion:
Using longitudinal data, we have demonstrated that hormonal contraceptive use declines over time within adolescent girls. In this population, decline in hormone use appears to be a function of desire for pregnancy and not a result of increased condom use.

Implications:
Desire for pregnancy competes with STD prevention efforts.