Ineffective Pregnancy Prevention During Adolescence: Assisting Healthcare Providers in Portugal With Individualized Risk Assessment.

In this study, we describe the relative contributions of and interactions between individual risk factors associated with ineffective pregnancy prevention among female adolescents in Portugal. Our sample consisted of 856 sexually experienced female adolescents (10-19 years) who did not intend to become pregnant. Of these, 379 were pregnant, and the residual (477) had never been pregnant. We used classification tree analysis to describe the interplay among a set of established sociodemographic, familial, reproductive, and relationship factors as predictors of ineffective pregnancy prevention. The tree model showed good predictive properties. Seven profiles predicted one-half to all the cases of ineffective pregnancy prevention. Ineffective pregnancy prevention was predicted by adolescents' grade level and different combinations of variables, specifically female age, age at the time of first sexual intercourse, religious beliefs, place of residence, maternal pregnancy before age 20, household structure in childhood, and partner's age difference. According to our findings, limiting assessments to the cumulative presence of risk factors may be insufficient to accurately identify adolescents at elevated risk of unwanted pregnancy, as the impact of any given risk factor may vary according to other factors. Our findings may contribute to the development of a risk assessment tool that may support healthcare providers' efforts to provide individualized risk assessment for adolescent patients and, thus, to better support pregnancy prevention.