Evolving Identities or Racial Misclassification? Fluidity in race response among American Indian birthing people in Michigan and implications for public health surveillance

We sought to characterize racial identity response transitions among multiparous birthing people who ever identified as American Indian or Alaska Native (AIAN) and assess whether this fluidity alters year-specific statewide AIAN maternal health and birth outcome prevalence estimates. To do so, we used Michigan birth certificates (2014-2022) to identify individuals with $\boldsymbol{\ge}$2 live births who self-reported as AIAN for $\boldsymbol{\ge}\mathbf{1}$ birth (n = 4823). We categorized individuals as having changed or not changed their reported racial identity across births and recalculated AIAN-specific outcome estimates accordingly. Only 23.9% (1155) consistently identified as AIAN across all births, while 76.1% (3668) used different racial identity responses. Among those whose racial identity response changed, transitioning from identifying as AIAN to no longer identifying as AIAN was the most common pattern. Accounting for these transitions had minimal effect on prevalence estimates for preterm birth and gestational diabetes, while there were some prevalence changes for the prevalence of smoking before/during pregnancy. AIAN birthing people in Michigan often shift racial identity responses over time. Although this fluidity had little impact on surveillance of perinatal outcomes, reliance on point-in-time race data may inadequately reflect AIAN identity in public health data.