A decomposition analysis to evaluate the role of social, chemical, and neighborhood factors on the Black/White disparity in preterm birth in Greater Houston, Texas

Background: Non-Hispanic Black women have almost double the risk of preterm birth compared with non-Hispanic White women in the United States, and the disparity is not fully explained by sociodemographic factors, health behaviors, or medical factors. Thus, it is critical to look beyond these “traditional” risk factors and evaluate contributions from psychosocial stressors, chemical exposures, and features of residential environments where pregnant women live. Methods: This study was conducted among 1,847 Black and White women recruited at the time of delivery between 2021 and 2023 in greater Houston, Texas to examine the contribution of individual- and neighborhood-level factors to the Black/White disparity in preterm birth using two-fold Blinder–Oaxaca decomposition. We evaluated the contribution from variables within the following domains: sociodemographics; perinatal history; comorbidities and health behaviors; chemical exposures; social factors; and neighborhood characteristics. We present the results as percent contributions to the disparity for each covariate and by domain. Results: With a 6.6% higher prevalence of preterm birth among Black mothers compared with White mothers, variables included in our decomposition analysis explained 63.0% of the preterm birth disparity, with perinatal history explaining the highest proportion (36.3%), followed by neighborhood characteristics (32.8%). Individual variables with the highest contributions included residing in a more racially minoritized and economically disadvantaged neighborhood (19.2%) and having a previous pregnancy complication (18.5%), a hypertensive disorder in the index pregnancy (16.7%), or chronic hypertension before pregnancy (16.8%). Conclusion: Our study underscores the importance of perinatal history and neighborhood factors in explaining disparities in preterm birth, which should be further explored in other populations.