Income Is Not an Equalizer: Uncovering Development Health Inequities By Ethnoracial Backgrounds in California Kindergartners over and Above Neighborhood-Level Income

Background: Developmental health, an important indicator for early childhood, increases with income. However, the strength of the relationship between developmental health and income varies by ethnoracial background. The purpose of this study is to determine the extent to which California kindergarteners face developmental health inequities by ethnoracial background and neighborhood income.

Methods: This cross-sectional study analyzed neighborhood-level income, developmental health, and ethnoracial data for California kindergarten to assess inequities. Student-level data (n = 106,574) were collected via surveys administered to teachers between 2010 to 2020 across 52 school districts and 964 schools. Student addresses were geocoded to facilitate place-based analyses. Developmental health was measured using the Early Development Instrument (EDI), a population-level measure which includes physical, social, emotional, language, and cognitive domains and is a strong predictor of later developmental outcomes. The primary outcome is “on-track” on all domains of the EDI.

Results: The analysis employs a Generalized Estimation Equation with a log-link function and interactions between ethnoracial background and income as well as income-squared. Marginal post-estimation commands allow for developmental health comparisons between ethnoracial groups across income gradients. Black and Hispanic students' average likelihood of being "on-track" is below the weighted average at all income levels, whereas Asian students are above the weighted average in all income levels (95% CI). The line for white students' developmental health has the steepest slope; white students at the lowest income levels have similar developmental health scores to their Black and Hispanic low-income counterparts, but are more similar to their Asian counterparts in high income levels.

Conclusion: This study provides a snapshot of California kindergartners’ ethnoracial and income -based developmental health inequities, showing that the relationship between neighborhood income and developmental health is weaker for students of color compared to white counterparts, and highlighting which ethnoracial groups are most likely to be on-track. While the early years of life are crucial for later health and life outcomes, few datasets offer population-level insight about developmental health. These place-based analyses can be used to better identify populations and neighborhoods in need of support in promoting developmental health.