Beyond Proxies: Environment, Neighborhood, and Racial Disparities in Hypertensive Disorders of Pregnancy

ABSTRACT Introduction Hypertensive disorders of pregnancy (HDP) are leading causes of maternal morbidity and mortality in the United States, with persistent racial disparities. Current clinical guidelines include "Black race" and "lower income" as proxy risk factors, which may lack precision and obscure structural and environmental contributors to HDP risk. This study evaluated environmental and neighborhood-level exposures as clinically accessible, structurally grounded risk factors for HDP that can be feasibly implemented in practice. Methods A retrospective cohort study was conducted among 619 pregnant patients receiving care within a Federally Qualified Health Center network. The primary outcome was HDP, defined as gestational hypertension or preeclampsia diagnosed during pregnancy, intrapartum, or postpartum. Address-linked exposures included high nitrogen dioxide (NO₂) pollution (≥5 ppb), high neighborhood poverty (>30% of residents below the federal poverty level), and zip code-level racial composition (majority White and majority Black/Hispanic zip codes). Associations with HDP were assessed in the full cohort and in race-stratified models, with and without adjustment for aspirin prescription. Odds ratios (ORs) with 95% confidence intervals (CI) were reported. Results Among 619 patients, 114 (18.4%) developed HDP. High NO₂ pollution was associated with the highest odds of HDP (OR 3.73, CI 2.43-5.79, p<0.001), followed by high neighborhood poverty (OR 2.21, CI 1.45–3.43, p<0.001). After adjustment for aspirin prescription, high NO₂ exposure remained the strongest risk factor (OR 2.88, CI 1.81-4.61, p<0.001). Residence in majority-White zip codes was protective for both Black (OR 0.41, CI 0.20–0.81, p=0.012) and non-Black (OR 0.37, CI 0.22–0.64, p<0.001) individuals. Conclusion High NO₂ pollution exposure and high neighborhood poverty were independently associated with increased HDP risk across racial groups, with NO₂ demonstrating the strongest association and effect size comparable to established clinical high-risk factors. Environmental and neighborhood-level measures may enhance HDP risk assessment beyond race- and income-based proxies and can be derived from routinely available address-linked data.