ABSTRACT: OBJECTIVE:To assess the relationships between self-reported psychosocial stress and preterm birth, hypertensive disease of pregnancy, and small-for-gestational-age (SGA) birth and to assess the extent to which these relationships account for racial and ethnic disparities in these adverse outcomes. METHODS:Self-reported measures of psychosocial stress (perceived stress, depression, racism, anxiety, resilience, and social support) were collected during pregnancy among a racially and ethnically diverse cohort of women enrolled in a prospective observational study of nulliparous women with singleton pregnancies, from eight clinical sites across the United States, between October 2010 and May 2014. The associations of preterm birth, hypertensive disease of pregnancy, and SGA birth with the self-reported measures of psychosocial stress as well as with race and ethnicity were evaluated. RESULTS:The study included 9,470 women (60.4% non-Hispanic white, 13.8% non-Hispanic black, 16.7% Hispanic, 4.0% Asian, and 5.0% other). Non-Hispanic black women were significantly more likely to experience any preterm birth, hypertensive disease of pregnancy, and SGA birth than were non-Hispanic white women (12.2% vs 8.0%, 16.7% vs 13.4%, and 17.2% vs 8.6%, respectively; P<.05 for all). After adjusting for potentially confounding factors, including the six different psychosocial factors singly and in combination, non-Hispanic black women continued to be at greater risk of any preterm birth and SGA birth compared with non-Hispanic white women. CONCLUSION:Among a large and geographically diverse cohort of nulliparous women with singleton gestations, non-Hispanic black women are most likely to experience preterm birth, hypertensive disease of pregnancy, and SGA birth. These disparities were not materially altered for preterm birth or SGA birth by adjustment for demographic differences and did not appear to be explained by differences in self-reported psychosocial factors.