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

Hypertensive disorders of pregnancy are leading causes of maternal morbidity and mortality in the U.S., with persistent racial disparities. Current clinical guidelines include Black race and lower income as proxy risk factors, which lack precision and may obscure structural and environmental contributors to hypertensive disorders of pregnancy risk. This study evaluated environmental and neighborhood-level exposures as clinically accessible, structurally grounded risk factors for hypertensive disorders of pregnancy that can be feasibly implemented in practice.

A retrospective cohort study was conducted among 619 pregnant patients receiving care within a Federally Qualified Health Center network. The primary outcome was hypertensive disorders of pregnancy, defined as gestational hypertension or preeclampsia diagnosed during pregnancy, intrapartum, or postpartum. Address-linked exposures included high nitrogen dioxide 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 or Hispanic ZIP codes). Associations with hypertensive disorders of pregnancy were assessed in the full cohort and in race-stratified models, with and without adjustment for aspirin prescription. ORs with 95% CIs were reported.

Among 619 patients, 114 (18.4%) developed hypertensive disorders of pregnancy. High nitrogen dioxide pollution was associated with the highest odds of hypertensive disorders of pregnancy (OR=3.73, 95% CI=2.43, 5.79, p<0.001), followed by high neighborhood poverty (OR=2.21, 95% CI=1.45, 3.43, p<0.001). After adjustment for aspirin prescription, high nitrogen dioxide exposure remained the strongest risk factor (OR=2.88, 95% CI=1.81, 4.61, p<0.001). Residence in majority White ZIP codes was protective for both Black (OR=0.41, 95% CI=0.20, 0.81, p=0.012) and non-Black (OR=0.37, 95% CI=0.22, 0.64, p<0.001) individuals.

High nitrogen dioxide pollution exposure and high neighborhood poverty were independently associated with increased hypertensive disorders of pregnancy risk across racial groups, with nitrogen dioxide demonstrating the strongest association and effect size comparable with that of established clinical high-risk factors. Environmental and neighborhood-level measures may enhance hypertensive disorders of pregnancy risk assessment beyond race- and income-based proxies and can be derived from routinely available address-linked data.