The Pediatric Paradox: Heterogeneity in the Birth Cohort

Timothy B. Gage, State University of New York at Albany

Racial comparisons of infant mortality indicate that low birth weight African American infants (the presumed disadvantaged population) have lower mortality rates than low birth weight European American infants. This paper explores the hypothesis that this "paradox" is due to heterogeneity. Analyses using Gaussian mixtures of logistic regressions suggests that birth cohorts are composed of two subpopulations heterogeneous for infant mortality. One subpopulation appears to account for the "normal" process of fetal development while the other may represent those "compromised" during development. Surprisingly, the "compromised" subpopulation has lower birth weight-specific mortality. This might be due to high rates of fetal loss in this subpopulation, which results in a highly selected birth cohort. Comparisons indicate that the Pediatric Paradox can be attributed to the larger "compromised" subpopulation with lower mortality of African Americans. This suggests that estimates of the disadvantage experienced by African Americans based on crude infant mortality rates are underestimated.