BACKGROUNDDespite medical and technological advances, the preterm birth rate among Black American women is 55% higher than white women. Prior evidence identifies various forms of racialized spatial inequality, especially residential segregation, that contribute to the persistent racial disparities in preterm birth. However, less is known about how dynamic processes of spatial inequality such as gentrification and Black migration impact preterm birth. PURPOSE The purpose of this project is to understand the relationship between two indicators of racial resegregation (gentrification and residential mobility) and preterm birth among Black women in Northern California. The specific aims are (1) to determine if gentrification stage is associated with preterm delivery among Black women; (2) to explore residential mobility patterns relative to racial resegregation and preterm birth among Black women and (3) Identify potential mechanisms linking regional inequality to preterm birth risk among Black women. METHODS Design: For Aim 1, I used a non-experimental cross-sectional design to explore the association between gentrification and preterm birth. For Aim 2, I used a retrospective cohort, matched sibling design to explore the relationship between inter-pregnancy residential mobility and preterm birth. For Aim 3, I used a grounded theory approach. Sampling and Sample: The quantitative component (Aims 1 and 2) drew samples from the San Diego Study of Outcomes in Mothers and Infants (SOMI) database. SOMI contains vital statistics records from all births in California from the years 2011-2017. The inclusion criteria were singleton births to Black individuals in the San Francisco Bay Area. The sample for Aim 1 is N=18,327. The sample for Aim 2 is N=4,910. The qualitative component involved primary data collection using semi-structured interviews with Black women (N=12), birth workers (N=2), maternal and child health experts (N=6), and urban scholars (N=4). Analysis: This study used multi-level logistic regression to examine the association between gentrification and preterm birth (Aim 1) and conditional logistic regression to analyze the relationship between residential mobility and preterm birth (Aim 2). The qualitative analysis was completed using realist ground theory. RESULTS Quantitative Findings: Residence in low-income neighborhoods with advanced gentrification was associated with lower odds of preterm birth (aOR= 0.818, 95% CI: 0.642,1.042). Housing insecurity partially suppressed the association. The relationship between residential mobility trajectory and preterm birth is conditional on WIC participation. Out-migration was only associated with preterm birth among non-WIC participants (aOR=1.548; 95% CI: 0.875,2.736). While moving between cities losing Black population was associated with higher odds of preterm birth for WIC participants (aOR= 3.481; 95% CI: 1.363,8.889). Qualitative Findings: Several processes linked regional inequality to preterm birth risk: Wealth and resource hoarding at different scales leaves Black birthing people with insecure access to health-promoting resources. Black women’s willingness and ability to engage in health and support services is hindered by the fragmentation of the social safety net and the policing of Black mothers in “care” settings. Landlord discrimination and exploitation geographically sorts and; and community-driven resistance and advocacy. DISCUSSION AND CONCLUSION The findings demonstrate that gentrification and residential mobility can influence preterm birth among Black individuals in the San Francisco Bay Area in unexpected ways. Major limitations include selection bias, the inability to measure housing tenure or mobility intention, and inadequacy of several measures including housing insecurity and social class. The findings in this study suggest that greater attention should be given to the forces that sort people into places and the policies that provide people with more control in their residential environments. Policies that maximize poor and working people’s ability to remain in or move to places that are supportive and safe may reduce chronic stress, and preterm birth among Black women in the Bay Area.