Low Pregnancy Cortisol and Infant Socioemotional Problems: The Mediating Role of Postpartum Depressive Symptoms.

Infant socioemotional development has important implications for later functioning, reflecting capacities for emotional regulation, stress responsivity, and social engagement. Stress and mental health during pregnancy and the postpartum can adversely influence infant socioemotional functioning. This study examined whether postpartum depressive and anxiety symptoms mediate associations between prenatal maternal hair cortisol concentration (HCC) and infant socioemotional development. A sample of 128 participants was followed from the third trimester of pregnancy to 6 months postpartum. Maternal HCC was collected during the third trimester to reflect cortisol during the second half of pregnancy. Symptoms of depression and anxiety were measured at 2 weeks postpartum, and infant socioemotional problems were assessed at 6 months of age. Structural equation modeling tested postpartum depression and anxiety as parallel mediators. Results indicated that lower HCC in pregnancy predicted greater postpartum depression (B = -3.676, p = 0.003) and anxiety (B = -3.41, p = 0.009); depression was associated with greater infant socioemotional problems at 6 months (B = 1.900, p < 0.001). HCC was not directly associated with infant socioemotional outcomes (B = 1.071, p = 0.792); however, the indirect effect, through depressive symptoms, was significant (B = -6.99, p = 0.01). These findings suggest that prenatal physiological stress may influence infant socioemotional development indirectly through early postpartum depressive symptoms, highlighting the importance of integrated perinatal processes.