PROJECT SUMMARY. Maternal mental illness following childbirth is associated with substantial societal costs. Postpartum psychopathology is a leading contributor of maternal morbidity and mortality and can endanger the child’s wellbeing onward from birth. Deprivation of maternal care during the early neonatal period can induce long-term epigenetic alterations in a model animal, suggesting that postpartum mental illness can confer intergenerational risks. While efforts exist to reduce postpartum depression, childbirth-related posttraumatic stress disorder (CB-PTSD), a condition that is estimated to affect 240,000 American women each year, is underdiagnosed and undertreated. Risk factors for CB-PTSD remain elusive, and knowledge about the disorder’s course and impact on the child is almost entirely lacking. By generating important and substantive data, the central objective of this proposal is to serve as a first step towards addressing the clinical gap for a condition that should be amenable to early intervention. In this first of its kind longitudinal prospective study, we will study pregnant women during third trimester (Wk. 32), again in the hours following delivery and will follow them at repeated time points across the postpartum (PP) year, i.e., Day 1, Day 45, and Mos. 3, 6, and 12. Their infants will be studied at Mo. 6 and Mo. 12 PP. This schedule will allow us to examine risk for, and development of, CB-PTSD, as well as its influence on mother- infant bonding and early child development. Maternal CB-PTSD will be quantified using psychodiagnostic, psychometric, and psychophysiologic measures. Psychophysiological responsivity during mental imagery of the traumatic childbirth provides a potentially reliable biological marker of PTSD and can provide objective validation of the CB-PTSD diagnosis. Bonding will be quantified using psychometric assessments of maternal perceptions and an observational assessment of mother-child interaction at 6 mos. PP. Child outcomes will be quantified using a standardized child developmental observational procedure and standardized psychometrics at 12 mos. This study will offer new insights into the previously understudied posttraumatic dimension of postpartum psychopathology. Our work could suggest modifications of postpartum mental health care, which currently focuses on depression. Our findings may inform tools that can be used for early screening that may be the first step in implementing programs that can enhance the welfare of mother and child, thereby reducing the odds of developing a potentially preventable, costly posttraumatic disorder. In addition, the proposed study will further the NICHD missions that “women avoid harmful effects from reproductive processes and children achieve healthy and productive lives”.