Early-life Mortality Trends in the United States between 1990 and 2024 - PROJECT SUMMARY This project examines early-life mortality trends in the United States (US) between 1990 and 2024. Findings from the project will provide the most detailed and comprehensive insight into the ways that changes in cause-specific death rates have reshaped early-life survival chances for American birth cohorts, and how these survival chances contrast with experiences in peer countries. The project will use official US mortality data at county, state, and national levels; national-level data for other high-income countries; and several US datasets containing county and states' demographic, economic, and sociopolitical indicators to examine how early-life US mortality trends have differed by sex, age, race/ethnicity, and across subnational regional contexts. In Specific Aim 1, we will estimate how causes of death have contributed to male and female US mortality trends in infancy (age 0), childhood (ages 1-14), adolescence/transition to adulthood (ages 15-24), and young adulthood (ages 25-44). We will also decompose US-peer differences in life expectancy by cause of death at these ages, thereby documenting how causes of death in early life have contributed to the widening US-peer longevity gaps in four time periods: 1990–1999, 2000–2009, 2010–2019, and 2019–2024. Through Specific Aim 2 we will broaden our investigations in Aim 1 to examine heterogeneity in these early-life trends by US state, sex, age, race/ethnicity, and SES levels across US county-groups. Critically, in both Aim 1 and Aim 2, we will examine US early-life mortality trends in a comparative and international context so that we produce knowledge about both absolute changes (e.g., how cause-specific death rates have changed over time for a specific US population) as well as relative changes (e.g., how US-peer differences in cause-specific death rates have changed over time). Thus, by contrasting US mortality trends against those experienced by populations in other high-income peer countries, the project will provide key insights into the characteristics, nature, and size of early-life mortality inequalities within the United States. In Specific Aim 3, we will estimate cohort differences in cause-specific death rates in early-life and calculate cohort-based changes in survival chances to midlife (i.e., to age 25, age 35, and age 45). Cohort analysis can actually reveal larger mortality changes – and larger mortality inequalities in these changes – than estimates derived from period-based analyses alone. Finally, in Specific Aim 4, We will estimate how changes in early-life cause-specific death rates in the United States and peer countries vary across birth cohorts and by time periods, providing key insights into the trends' causes. By examining early-life mortality trends in the United States through both (i) a cohort framework, and (ii) within an international context, this project will significantly improve our understanding of recent changes in cause-specific mortality among young US populations, and how these changes contribute to the US longevity disadvantage as well as contribute to widening mortality inequalities within the United States.
