Despite improvements in prenatal care, the rate of poor pregnancy outcomes such as preterm birth (PTB; < 37 weeks gestation) and low birth weight (LBW) remains high in the United States. This project will provide important evidence concerning the relationships between antenatal maternal mood disorders, pregnancy-specific stress, and poor pregnancy outcomes, as well as what these relationships mean for infant immunologic and neurobehavioral development. The proposed research will test the hypothesis that prenatal maternal mood disorders (anxiety and/or depression) and symptoms increase the risk of poor pregnancy outcomes and compromise infant behavioral and immunological development in the first year of life, and that activation of the HPA axis and increased inflammatory activity in the perinatal period plays a significant role in these effects. Notably, although previous work has examined the role of overall stress (i.e., perceived stress, life events) in pregnancy and infant outcome the present study builds on the research team's prior work to assess the importance of emotional states specific to pregnancy (i.e., pregnancy-specific anxiety and distress) in the effects of mood on pregnancy and infant outcome. Completion of the proposed studies will advance the understanding of the psychoneuroimmunology of pregnancy and provide prospective evidence of the effects of prenatal maternal mood and pregnancy-specific stress on birth and infants' immunological and behavioral development in the first year of life. Moreover, the richness of the resulting dataset will allow us to conduct additional exploratory analyses to investigate (1) the role of vitamin D i the relationships under investigation, given growing evidence of its involvement in inflammation, mood disorders, and birth outcome; (2) if and how residence at moderate altitude (5280 feet above sea level) may play a role in these effects; and (3) how prenatal maternal biopsychosocial variables may impact maternal mood, stress, and neural-immune status in the postpartum. To summarize, this project will provide new data about how maternal mood translates into changes in infant health and pregnancy outcome, the physiological systems involved in these effects, and how emotional states of pregnancy play into these effects. These data will support care of pregnant women's mental health, and may ultimately help to reduce the occurrence of poor pregnancy and infant outcomes, especially in populations that are more likely to have higher-than-average levels of stress and mood symptoms.