Divergent Trends in the Effects of Early-Life Factors on Adult Health.

Life course theories have shaped social and health scientists' understanding of the origins and pathways of health, aging, and mortality. However, few studies have examined how these origins might have changed across cohorts. This study investigates the impact of birth, childhood, and adolescence factors on adult health across birth cohorts born in the second half of the 20th century in the United States. Data come from the Panel Study of Income Dynamics Family and Individual Files 1968-2013 and the Childbirth and Adoption History File 1985-2013. Multilevel growth models are used to capture the growth trajectories of two adult health outcomes: self-rated health and health summary index. We find the association between three pre-adulthood factors (birth weight, mother's education, childhood family income-to-needs ratio) and health outcomes weakens in more recent cohorts, while the association strengthens for the other two early life factors (early-life disease index and parental smoking status before age 17). These findings demonstrate the complexity of the social-to-biological embodiment across the life course, and suggest that the effects of early-life factors on adult health can increase or decrease across cohorts due to macro social, economic, policy, technological, and medical changes. They also illuminate the long-term debate on the period and cohort effects in shaping the health trend, and suggest that the cohort effect is multidimensional and is weaker or stronger depending on the dimension of early life examined.