Is Segregation Bad for Your Health? The Case of Low Birth Weight

This paper explores the relationship between racial segregation and racial disparities in the prevalence of low birth weight. The paper has two parallel motivations. First, the disparities between black and white mothers in birth outcomes are large and persistent. In 1996, 13 percent of infants born in the United States to black mothers weighed less than 2,500 grams (5.5 pounds, or low birth weight), compared with just 6.3 percent of all infants born to white mothers. And the consequences may be grave. Low birth weight is a major cause of infant mortality and is associated with greater childhood illness and such developmental disorders as cerebral palsy, deafness, blindness, epilepsy, chronic lung disease, learning disabilities, and attention deficit disorder. ¹ Given the strong connection between race and residence in this country, it seems plausible that residential location may shape these differentials.

Second, while there is a growing literature on the costs of racial segregation, it has largely focused on economic outcomes such as education and employment. This paper aims to develop a fuller understanding of the costs of racial segregation by considering birth outcomes as well as such behaviors as tobacco and alcohol use among pregnant mothers. As Glaeser emphasizes (in his paper in this volume), information, ideas, and values are often transmitted through face-to-face interaction, and thus their transmission may be blocked by segregation. This includes information related to job openings and may include information and norms related to behavior and care during pregnancy.

Adopting in large part the methodology of David Cutler and Edward L. Glaeser, the paper thus examines how levels of racial segregation affect the birth outcomes of black mothers. ² It examines influences on both black and nonblack mothers in an attempt to identify the differential effect of segregation on black mothers.

Theory and Past Literature

This section summarizes what is known about the costs of segregation from prior research, discusses several alternative pathways through which segregation may influence outcomes, and reviews previous literature on the causes of low birth weight. Given this understanding, the section then explores how segregation might contribute to the lower birth weights of infants born to black mothers.

Costs of Racial Segregation

There is a growing body of work demonstrating a negative correlation between the degree of racial segregation in a metropolitan area and the economic success of its African American population. ³ Parallel to this work is a growing literature suggesting a link between racial segregation and the health of African Americans. In more segregated neighborhoods and metropolitan areas, African Americans have been found to suffer higher rates of homicide, suicide, infant mortality, and overall age-adjusted mortality. ⁴

While these correlations are striking both in magnitude and significance, determining the direction of causality is naturally more difficult. It may be that greater disparities in economic status lead to greater residential segregation and not the reverse. And the link between segregation and health outcomes may simply reveal that blacks who are more economically disadvantaged tend both to be at greater risk of poor health outcomes and to live in more segregated areas.

Despite this ambiguity, researchers considering health outcomes and segregation have paid scant attention to the issue of causality. They tend to rely strictly on aggregate, cross-sectional correlations, and thus it is difficult to interpret their results. The researchers concentrating on employment and education have focused a great deal more on causality and have made substantial strides. ⁵ Cutler and Glaeser make the most thorough attempt to discern causality. ⁶

First, they study cross-metropolitan area differences in segregation. Many prior studies examining the effects of segregation have focused on a particular city or metropolitan area and compared the outcomes of blacks living in neighborhoods of varying racial compositions. ⁷ This approach may overstate the effects...