Abstract

Introduction: Adolescent pregnancy has persisted as a public and social health problem in Chile, affecting the most vulnerable adolescents and reflecting inequalities. Objective: To describe the changes in the use of contraceptives, unplanned pregnancies and children in Chilean adolescents between 1997 and 2018. Method: Ecological study of time series between the years 1997 and 2018. The association between sociodemographic variables and the effectiveness of the contraceptive method for the years 2006 and 2018 was measured using the Rao-Scott statistical test. Trends in the percentage of use of contraceptive methods were estimated according to their efficacy and presence of unplanned pregnancies and children with linear regression models (Prais-Winsten method). Results: An increase in the frequency of sexually active adolescents and the use of contraceptives, especially pills and injectables, was observed. The time series of contraceptive use was non-stationary, the trend was increasing (coefficient: 4.59; 95% confidence interval [95%CI]: 3.43-5.74; p = 0.001), increasing 4.59% every three years. The time series, unplanned pregnancies and having children were non-stationary time series, both showed a decreasing trend (coefficient: -4.78; 95%CI: -6.32 to -3.24; p = 0.002; and coefficient: -3.93; 95%CI: -6.18 to -1.68; p = 0.008), decreasing 4.78% and 3.93%, respectively, every 3 years. Conclusions: The increase in the use of contraceptives in adolescents has been linked to a significant decrease in unplanned pregnancies and children in this population.