This dissertation proposes a novel framework for understanding Asian American (AsA) heterogeneity, shaped by colonialism, immigration, and racism. From this grounding, this body of work advances knowledge of perinatal health among AsA subgroups and its association with residential segregation-- a key driver of racial health inequities. Through empirical analysis, this research shows that segregated AsA neighborhoods, like its population, are diverse and have varied associations with preterm birth, a critical public health issue. This work emphasizes the urgent need for systematically disaggregating racial data in public health research and reporting to reveal hidden disparities and inform equitable health strategies.