The Association Between Structural Disadvantage and Adverse Birth Outcomes: Analyzing Preterm Birth and Low Birth Weight Using the Structural Racism Effect Index.

Patterns of risk for adverse birth outcomes, including low birth weight and preterm birth, are influenced by structural disadvantage. The Structural Racism Effect Index (SREI) measures these disadvantages across nine different domains, including education, income, housing, and employment. This study examines the association between structural disadvantage, as measured by the SREI, and adverse birth outcomes in the USA. Using the National Center for Health Statistics' 2020 natality file, modified Poisson regression models with robust variance adjusted for maternal age, education, prenatal care initiation, previous preterm birth, and payment source estimated the relative risks of low birth weight and preterm birth associated with exposure to level of SREI at the maternal county of residence. Among 2,376,030 birth records, higher SREI scores were significantly associated with increased risks of adverse outcomes. Medium and high SREI levels were linked to 7.4% (95% CI 6.3-8.5%) and 18.8% (95% CI 16.9-20.8%) higher risks for preterm birth, respectively, and 6.1% (95% CI 4.9-7.2%) and 17.0% (95% CI 15.8-18.2%) higher risks for low birth weight, respectively, compared to low SREI scores. Stratified analyses revealed that the impact of SREI on adverse birth outcomes varied significantly by maternal race, highlighting differential effects across racial groups. Cuzick's test for linear trend confirmed the dose-response relationship between the extent of structural disadvantage and the likelihood of adverse birth outcomes.