Gestational diabetes mellitus (GDM) impacts an estimated 3% to 9% of pregnancies, increasing the risk of serious health complications for mother and child. The identified risk factors for developing GDM include both individual characteristics (e.g., higher body mass index, advanced maternal age) and heritable factors (e.g., family history of Type 2 diabetes, historically marginalized racial/ethnic identity). However, approximately 50% of GDM diagnoses occur in the absence of any known risk factor(s). Additional research on biopsychosocial factors related to glucose metabolism, such as mental health and stress processes, may help to identify individuals at risk. We hypothesize that there will be associations between maternal mental health, glucose metabolization, and GDM related adverse pregnancy outcomes that are moderated by stress, and that the magnitude of the of these associations underlay GDM health disparities experienced by African American (AA) and Native American (NA) women in comparison to non- Hispanic white (NHW) women. This project will: 1) identify stress-related variables that moderate associations between maternal mental health and GDM-related health outcomes; 2) delineate associations among maternal mental health, stress, glucose metabolization, and related adverse outcomes, differ among AA, NA, and NHW women; and 3) increase our understanding of how psychophysiological stress reactivity interacts with maternal stress and mental health, to predict glucose metabolization during pregnancy, and associations with adverse perinatal outcomes. A retrospective study of 4,845 de-identified pregnancy-related medical records of Sanford Health patients, and a prospective study which follows 150 pregnant women recruited from Sanford Health prenatal care providers will be conducted. Data from medical records and prospective assessments will be used to identify associations between maternal health, mental health, blood glucose metabolization and pregnancy outcomes. Indicators of stress will be tested as moderators in these associations. These analyses will identify which combinations of maternal depression, anxiety, and stress, are associated with increased risk of GDM and GDM related outcomes. The retrospective study will compare the impact of modeled associations, among women of NA, AA, and NHW heritage, with results that will provide insights as to the role of psychosocial factors in GDM related health disparities among AA and NA women. The prospective study, participants will complete a laboratory stress task while we assess physiological markers of stress reactivity. Results from the prospective study will provide novel information about the role of physiological pathways by which combinations of maternal mental health and stress impact blood sugar metabolization. We aim to improve our ability to identify women at risk and prevent GDM and related complications.