Selection and population health: Theory and typology of research.

Public health researchers may assume, based on the fetal origins literature, that "scarring" of birth cohorts describes the population response to modern-day stressors. We contend, based on extensive literature concerned with selection , that this assumption remains questionable. At least a third and likely many more of human conceptions fail to yield a live birth. Those that survive to birth, moreover, do not represent their conception cohort. Increasing data availability has led to an improved understanding of selection and its implications for population health. The literature describing selection , however, receives relatively little attention from social scientists. We aim to draw attention to the rich theoretical and empirical literature on selection by offering a typology that organizes this diverse work along dimensions we think important, if not familiar, to those studying population health. We further use the typology to identify important gaps in the literature. This work should interest social scientists for two reasons. First, phenomena of broad scholarly interest (i.e., social connectivity, bereavement) affect the extent and timing of selection . Second, the life-course health of a cohort depends in part on the strength of such selection. We conclude by identifying new research directions and with a reconciliation of the apparent contradiction between the "fetal origins" literature and that describing selection .