摘要：Objectives. We examined potential synergistic effects of racial and socioeconomic inequality associated with small-for-gestational-age (SGA) birth. Methods. Electronic medical records from singleton births to White and Black women in 10 US states and the District of Columbia (n = 121 758) were linked to state-level indicators of structural racism, including the ratios of Blacks to Whites who were employed, were incarcerated, and had a bachelor’s or higher degree. We used state-level Gini coefficients to assess income inequality. Generalized estimating equations models were used to quantify the adjusted odds of SGA birth associated with each indicator and the joint effects of structural racism and income inequality. Results. Structural racism indicators were associated with higher odds of SGA birth, and similar effects were observed for both races. The joint effects of racial and income inequality were significantly associated with SGA birth only when levels of both were high; in areas with high inequality levels, adjusted odds ratios ranged from 1.81 to 2.11 for the 3 structural racism indicators. Conclusions. High levels of racial inequality and socioeconomic inequality appear to increase the risk of SGA birth, particularly when they co-occur. In the United States, Black women are more than 1.5 times as likely as White women to give birth to a small-for-gestational-age (SGA) infant, typically defined as an infant with a birth weight below the 10th percentile for a given gestational age; such births increase the risk of neonatal morbidity and long-term deficits in growth and development. 1 This disparity has persisted for decades and is not fully explained by differences in health behaviors or access to prenatal care. 2–4 Although individual socioeconomic status attenuates some of the increase in risk experienced by Black women, residual disparities remain. 5 Racial discrimination may be a distinct and critical source of chronic stress among women of color, both during pregnancy and across the life course. 6 Disparities in perinatal outcomes, including SGA birth, are of particular interest to researchers concerned with the potential health effects of discrimination. A growing body of research has identified the harmful effects of racial discrimination on the health of Blacks in the United States. 7 Evidence suggests that discrimination may be at least partially responsible for the large and persistent disparities in morbidity and mortality that exist between Whites and Americans of color. 8 Much of this research has focused on individual experiences of discrimination, but a relatively recent paradigm shift has begun to identify such experiences as part of a larger system of policies and practices that reinforce racial inequity. 9 This system refers to the concept of structural racism, defined as the exclusion of racial minorities from resources and opportunities (e.g., wealth, housing, education), effectively creating a health disadvantage. 10 The historical legacy of racial oppression experienced by Black Americans 9,11 and persistent differences in access to resources have resulted in a system of strong links between race and social class at the population level. Inequalities in health therefore are not driven by race or class alone, 12 and disentangling the health effects of both racial and socioeconomic disadvantage continues to present conceptual and methodological difficulties. 13 Previous work highlighting the detrimental effects of structural racism on pregnancy outcomes, including infant size and gestational age at delivery, has been largely limited to analyses of neighborhood or metropolitan area contexts such as segregation patterns, 14–19 deprivation, 20–23 and crime, 24 which may stem from, for example, discriminatory mortgage lending, population differences in buying power, and federal housing policies. 25 Furthermore, studies that have considered contextual socioeconomic characteristics have produced inconsistent results in terms of the degree to which these factors explain racial disparities in adverse birth outcomes between neighborhoods. 15,19,21 It remains unknown whether structural racism measured at the state level is associated with SGA birth. In a recent investigation of structural racism and myocardial infarction, Lukachko et al. developed a series of state-level indicators intended to represent the systematic exclusion of people of color from access to resources, opportunities, and social mobility. 26 Using similar indicators, we investigated the potential synergistic effects of state-level structural racism and socioeconomic inequality on the risk of SGA birth among White and Black women in a large US obstetrical cohort study. We aimed to describe the degree of structural racism across the study states, determine whether the effects of structural racism differed according to maternal race and across levels of income inequality, and quantify the risk of SGA birth associated with high levels of both racial and socioeconomic inequality.
