Racial disparity and environmental influences on perinatal health in Jefferson County, Kentucky.

Background: Severe maternal morbidity (SMM) risk has tripled over the past 30 years. Adverse infant birth outcomes in the U.S. have also increased with substantial Black-White disparities. Objectives: This work compares the frequency of adverse maternal and infant birth outcomes by maternal race (Black vs White) and examines associations between maternal ambient heavy metal exposures and birth outcomes in Jefferson County, Kentucky, 2017-2022. Methods: Jefferson County inpatient hospital delivery and birth certificate records of self-identified Black or White birthing parents were used. Incidence of SMM, stillbirth, preterm birth (PTB), and small for gestational age (SGA) with 95% confidence intervals (CI) were estimated overall and by race. Logistic regression was used to estimate odds ratios (ORs) and 95% CIs, comparing the odds of each outcome by race (Black vs. White) and composite scores of ambient heavy metals adjusted for a set of explanatory variables and pandemic effects. Results: Racial disparity was found in all birth outcomes after adjusting for maternal, infant, and healthcare factors. Comparing Black to White, Black deliveries and births had 50% higher adjusted odds of SMM (OR 1.5, 95%CI 1.2, 1.9); 40% higher odds of stillbirth (OR 1.4, 95%CI 1.1,1.7) and PTB (OR 1.4, 95%CI 1.3, 1.5); and over twice the odds of SGA (OR 2.3, 95%CI 2.1, 2.4). We found significant associations between ambient heavy metal composite scores and risk of PTB for Black birthing parents; there were 40% higher odds of PTB (OR: 1.4, 95%CI 1.1, 1.7) and 30% higher odds of SGA (OR 1.3, 95% CI 1.1,1.4) for those with Very High exposure compared to those with Low exposure. Among births to Whites, Very High ambient heavy metal exposure was associated with 40% higher odds of SGA (OR 1.4, 1.95% CI 1.1,1.6) compared with Low exposure. Conclusion: Findings confirm substantial Black-White disparities in SMM and adverse birth outcomes, specific associations between ambient heavy metals and adverse birth outcomes that varied by race. Further research should explore potential mechanisms underlying these associations and interventions that may reduce such exposures to promote equitable birth outcomes.