Racial residential segregation and adverse birth outcomes: A systematic review and meta-analysis.

Rationale: Persistent racial disparities in adverse birth outcomes are not fully explained by individual-level risk factors. Racial residential segregation-degree to which two or more groups live apart from one another-may contribute to the etiology of these birth outcome disparities. Our aim was to assess associations between segregation and adverse birth outcomes by race. This review focused on formal measures of segregation, using Massey and Denton's framework (1998) that identifies five distinct operationalizations of segregation, in addition to proxy measures of segregation such as racial composition, in order to gain a deeper understanding of the operationalizations of segregation most salient for birth outcomes.

Method: Review and meta-analyses were conducted using PubMed, PsycINFO and Web of Science and included articles from inception through April 30, 2017.

Results: Forty-two articles examined associations between segregation and adverse birth outcomes among Black and White mothers separately. Meta-analyses showed that among Black mothers, exposure was associated with increased risk of preterm birth (OR = 1.17, 95% CI = 1.10, 1.26), and low birth weight (OR = 1.13, 95% CI=1.06, 1.21), and Black racial composition was associated with increased risk of preterm birth (OR = 1.20, 95% CI=1.05, 1.37), among those living in most- compared to least-segregated neighborhoods. Few studies were conducted among White mothers and only exposure was associated with increased risk of preterm birth and low birth weight. Qualitative analyses indicated that among Black mothers, exposure and hypersegregation were associated with multiple adverse birth outcomes; findings were mixed for evenness and clustering.

Conclusions And Future Directions: Associations between segregation and adverse birth outcomes differ by race. Methodological heterogeneity between studies may obscure true associations. Research can be advanced through use of multilevel frameworks and by examining mechanistic pathways between segregation and adverse birth outcomes. Elucidation of pathways may provide opportunities to intervene to reduce seemingly intractable racial disparities in adverse birth outcomes.