PROJECT SUMMARY/ABSTRACT Despite the well-known Latina birth paradox, recent data (2020) show that Latina mothers are 1.2-1.5 times more likely to have low birth weight infants compared to White mothers. Additionally, compared to White women, annual national vital statistics data from 1989 through 2020 show consistently higher rates of worse birth outcomes among Latinas. The longstanding focus on the Latina birth paradox has left a gap in the literature, resulting in a critical need for research on birth outcome disparities faced by Latinas, and the mechanisms driving those disparities. We propose two novel mechanisms as contributors to poor birth outcomes for Latinas: anticipatory racism threat and area-level racial bias. A strong body of evidence has demonstrated links between chronic social stress and poor birth outcomes. Racial discrimination, a chronic psychosocial stressor, is a prominent explanation for racial/ethnic disparities in birth outcomes. However, evidence is limited by the predominant focus on racism events and racism experiences at the individual-level. We previously developed and validated a measure of anticipatory racism threat (aRT) for African American women and found associations with hypertension, allostatic load and telomere length. These preliminary studies suggest that anticipating racism, above and beyond actual racism events, is related to biological dysregulation, including dysregulation of systems that have previously been linked with low birthweight and preterm birth. Another neglected component of racism-related stress is area-level racial bias. Emerging evidence demonstrates significant links between negative area-level racial sentiment and birth outcomes for racial/ethnic minorities groups. The specific objectives of the K99 phase are to 1) create and psychometrically validate an aRT-Latina scale and 2) examine associations with low birth weight and preterm birth in recent Latina mothers. R00 phase objectives include developing and testing associations between a novel county-level indicator of area-level racial bias towards Latines and county-level birth outcomes among Latinas. The expected impact of the proposed research is re-focusing attention on poor birth outcomes among Latinas, a long-standing disparity but largely neglected area of investigation; helping to elucidate some of the predictors and underlying mechanisms driving those disparities; and ultimately informing the types of interventions likely to ameliorate those disparities. These data will also provide preliminary data for a subsequent R01 application. Our central hypothesis is that higher anticipatory racism threat and more negative area-level racial bias toward Latines will predict worse birth outcomes (i.e., low birth weight and pre-term birth) for Latina mothers.