Research Day


Differential Pathways to Infant Health, by Race and by Income

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INTRODUCTION: Within Kalamazoo County, as across the nation, infants of color die at markedly higher rates than white infants. This disparity grows as income increases; with improved health among higher-income white infants but not among higher-income infants of color. Not only do high- and low- income infants of color die at different rates than their white counterparts, but they die from different causes. STUDY OBJECTIVE: The goal of the current investigation was to examine whether county variations in infant mortality by race and income were explained by differential predictors (maternal demographics and health indicators). METHODS: This observational study utilized a cross-sectional design with secondary data analysis of infant birth and death vital records. The study population was all infants born to Kalamazoo County residents during the study period, 2008 through 2014 (N=21,858). The study outcome was infant health, as defined by full-term gestation (>37 weeks), adequate birthweight (>2,500 grams) and infant survival to first birthday. Predictors included maternal demographics, health risk and prenatal care. Predictive models were stratified by race (of color, white) and income (Medicaid, private insurance) with two-sided statistical significance set at p<.05. RESULTS: Prior to stratification, multivariable logistic regression models confirmed that the race-by-income interaction remained a significant predictor of infant health: higher-income white infants had the best health, followed by low-income white infants and higher-income infants-of-color who had similar health status, and low-income infants-of-color with the worst health (Wald Chi Square 85.28, p<.0001). With few exceptions, prevalence of risk factors varied by socioeconomic status: higher-income women, regardless of their race, had fewer risk factors (e.g., adolescent pregnancy, prior poor birth outcome, chronic disease, prenatal care, STI, prenatal smoking, etc). Excessive or inadequate prenatal visits, prior poor birth outcomes and chronic disease were important predictors for all individuals; however the degree to which they predicted outcomes varied by both race and income: • Excessive prenatal visit and obstetric medical risk had the strongest predictive value for higher-income white infants • Maternal underweight presented the greatest risk for low-income white infants. This was also the only group for whom prenatal smoking was a significant risk factor. • Having a prior poor birth outcome presented the greatest risk for infants of color, regardless of income CONCLUSION: Infant health predictors vary by race and, among whites, by income. Achieving equity will depend upon structuring resources to meet the nature and degree of risk specific to each population.

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