BackgroundSubstantial research documents health consequences of neighborhood disadvantage. Patterns of residential mobility that differ by race/ethnicity and socioeconomic status (SES) may sort non-Hispanic (NH) Black and low-SES families into disadvantaged neighborhoods. In this study, we leverage a sibling-linked dataset to track residential mobility among birthing persons between pregnancies and investigate baseline characteristics associated with downward mobility, including race/ethnicity, SES, and pre-existing health conditions. MethodsWe used a probabilistic linkage strategy to identify births to the same person between 2007 and 2015 (n = 624,222) and categorized downward residential mobility by quartile-level increases in neighborhood disadvantage. We defined strong downward mobility as a move from a neighborhood with very low (quartile 1) to very high (quartile 4) disadvantage and estimated the logit (i.e., log-odds) of strong downward mobility as a function of racial/ethnic, sociodemographic, and health characteristics of the birthing person and their first birth. We further explored the role of neighborhood housing affordability by examining changes in affordability from first to second birth by race/ethnicity. ResultsNH Black birthing persons show an over three-fold increased odds of strong downward mobility relative to NH white birthing persons (OR = 3.34, CI: 2.91, 3.84). To a lesser extent, Hispanic race/ethnicity, WIC receipt, low educational attainment, obesity, and infant preterm birth (PTB) also predict strong downward mobility. Examination of changes in neighborhood affordability indicate that over half of NH Black birthing persons move to a more affordable neighborhood, compared to less than a quarter of NH white birthing persons, before the birth of their second child. Results remain consistent across outcomes, measures of neighborhood SES, and modified log-Poisson models. ConclusionWe find an elevated risk of strong downward mobility among NH Black and low-SES birthing persons. Future research may identify other factors (e.g., housing affordability) that generate downward residential mobility to identify interventions that promote neighborhood equity.