Sex Differences in U.S. Adolescent and Young Adult Mortality.

U.S. females live longer than males due to a range of social, psychological, behavioral, and health factors. Prior research has underscored unhealthy behaviors as particularly risky for males and lower socioeconomic status as a risk factor for females in shaping sex differences in adult mortality. But this research has largely examined mortality during mid- and older-adulthood, with most deaths occurring at older ages. Our study focuses on sex differences in mortality among a cohort of U.S. adolescents followed into adulthood, ages 12-46 (N=18,921). We employ Cox proportional hazard models and data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), which was recently linked to mortality records through December of 2021. The hazard of dying is much greater (HR=1.69; p<.001) for male compared to female adolescents and young adults, with larger disparities for external compared to internal causes of death. Sex differences in mortality are reduced but persist when controlling for childhood experiences, health behaviors, risky behaviors, and social ties. The relatively poor mental and physical health of females suppresses the differences; that is, sex differences in mortality would be even larger were it not for the poorer mental and physical health of young females compared with males. The findings point to risk factors that if improved could reduce mortality for both U.S. males and females, while reducing sex differences in mortality among younger adults. Such improvements could increase life expectancy of the U.S. population and reduce mortality and sex differences at older ages.