ABSTRACT A growing number of studies has implicated maternal stress as an explanation for the higher burden of adverse pregnancy outcomes (APOs) seen among non-Hispanic Black women compared with their non-Hispanic White counterparts. Most studies that have explored the relationship between stress and APOs have focused solely on prenatal exposure to stressors, but Black women are generally exposed to more stressors over the life course than White women. Moreover, Black women may have more limited resources to cope with social stressors, as well as be more likely to experience enduring stressors like racial and/or gender discrimination, which may lead to dysregulated physiological and psychological responses to everyday stressors (i.e., stress reactivity). Several studies have shown dysregulated cardiovascular, neuroendocrine, and affective reactivity to stressors is associated with increased CVD risk and other adverse health outcomes in non-pregnant populations, but the impact of dysregulated stress reactivity on pregnancy outcomes remains poorly understood. Thus, the overall goal of this study is to examine the impact of physiological and psychological stress reactivity on adverse placental and pregnancy outcomes. We will use ecological momentary assessments and intensive measurements of heart rate variability, blood pressure, salivary cortisol, and positive and negative affect to generate personalized measures of how pregnant women respond to stressful experiences in their daily lives. We will then examine associations of these measures with adverse placental lesions and pregnancy outcomes. Finally, we will quantify the extent to which stress reactivity and exposure to stressors during pregnancy account for racial disparities in these adverse outcomes.