Time Trends and Socioeconomic Inequalities in Parental Physical Aggression and Adolescent Physical Fighting: Three Brazilian Birth Cohort Studies Over Twenty Years, 2000-2020.

Purpose: Violence prevention requires robust data on trends in different forms of violence and measures of progress toward reduction across subgroups of the population. This study aimed to investigate trends and related socioeconomic inequalities in parental physical aggression and involvement in physical fights among adolescents.

Methods: Three population-based birth cohorts were conducted, including all births in the calendar years 1982, 1993, and 2004 in Pelotas city, Southern Brazil, with over 4,200 births in each cohort. Confidential self-report questionnaires were used to measure parental physical aggression (ages 11 and 15 years) and involvement in physical fights (ages 11, 15, and 18). The prevalence of violence outcomes was estimated, stratifying by sex and family income group for each cohort, and income-related inequalities were assessed through time.

Results: There were significant reductions in parental physical aggression between cohorts, at ages 11 (prevalence ratio (PR): 0.83) and 15 years (PR: 0.70), and there was some evidence of reductions in income-related inequality regarding harsh parenting, mainly for boys. Considering physical fighting, there was a small increase through time for boys at age 11 (PR: 1.22), but no change for either sex at age 15, and declines for girls at age 18 years (PR: 0.50). There were income inequalities in physical fighting for girls at ages 11 and 15 (with a higher prevalence among the poorest adolescent girls in comparison to the richest), which persisted through time. However, income inequality in fighting among girls at age 18 reduced through time. There was little income inequality in fighting among boys at any age in any cohort.

Discussion: Encouraging declines in parental physical aggression have occurred over the past 2 decades in this population of adolescents, but there is less clear evidence of changes in physical fights. Continued monitoring is vital to inform violence prevention policies.