Explaining Racial and Ethnic Disparities in Hypertension and Diabetes during Pregnancy in the United States (2016-2022): A Decomposition Analysis.

Although prior research has identified some risk factors for pregnancy complications, little is known about their role in explaining the temporal changes in these complications. This study examines recent trends in two major pregnancy complications-hypertension and diabetes-in the United States, with a focus on racial/ethnic disparities. Guided by the perspectives of social conditions and structural racism, we assess how changes in maternal characteristics and their differential associations with health outcomes contribute to these disparities over time. We hypothesize that the rising prevalence of pregnancy complications and the widening racial and ethnic disparities reflect not only who has which characteristics, but also systemic processes that translate those characteristics into differential risk. Using data from the CDC natality files covering nearly all live births from 2016 to 2022 in the U.S., we applied decomposition techniques to analyze the contributions of both the distribution of maternal characteristics and their effects to these disparities. Findings indicate an overall rise in both complications across all racial/ethnic groups, with disparities widening over time. While compositional changes in maternal characteristics explain a modest portion of these trends, a significant share is attributed to shifting coefficient effects, suggesting a deteriorating maternal health environment. Decomposition analyses show heterogeneity in the contributions of compositional and coefficient effects across racial/ethnic groups. Maternal characteristics substantially explained disparities such as AIAN-White hypertension and Hispanic-White diabetes in 2022, while differential responses to health factors primarily explained gaps such as Black-White hypertension and Asian-White diabetes. Temporal decomposition revealed that coefficient effects were the main driver of widening Black-White hypertension and Asian-White diabetes gaps. The COVID-19 pandemic exacerbated these trends, intensifying disparities during periods of heightened healthcare strain and social inequality. Our findings suggest that addressing pregnancy-related health disparities requires not only reducing unequal exposures but also confronting structural conditions that produce inequitable health returns, even among similarly situated individuals, emphasizing the importance of equitable access to medical advancements and targeted policy interventions.