Psychobiological Mediators of the Impact of Pregnancy Stress on Maternal Sensitivity - PROJECT SUMMARY Poor mental health is prevalent in stressful pregnancies, with at least 10-15% of pregnant women above the clinical thresholds for a mental health disorder. Mothers affected by mental health disorders are less likely to engage in sensitive caregiving and may be at risk for engaging in harsh and punitive behaviors that lead to a host of poor child outcomes. Pregnancy stress also disrupts the endocrine profile of pregnancy, which is highly problematic because circulating estradiol and progesterone across pregnancy are known to be strong biological determinants of early postpartum caregiving in humans and all other mammals. While maternal mental health and sex steroids across pregnancy are each affected by stress and influence postpartum caregiving, how they coordinate with each other to impact early maternal sensitivity is completely unknown. We hypothesize in this R03 project that maternal mental health symptoms and maternal sex steroid hormones are critical biopsychosocial mediators of the relationship between pregnancy stress and low maternal sensitivity. The Specific Aims of this proposed basic research project are to: 1) Determine the individual trajectories, and coordinated changes in trajectories, of mental health symptoms (i.e., depression, trait anxiety, pregnancy-specific anxiety, PTSD) and sex steroid hormones (estradiol, progesterone, and their ratio) across pregnancy to early postpartum, and 2) Determine whether these trajectories, including changes over time, mediate the relationship between pregnancy stress and postpartum maternal sensitivity. The proposed project will be the first longitudinal, prospective study determining how the trajectories of maternal mental health symptoms and sex steroid hormones (alone and coordinating together) mediate the relationship between pregnancy stress and maternal sensitivity in an economically, educationally, and racially heterogeneous sample of women. Our proposed study's secondary analysis will capitalize on multi-method data previously collected through our team's ongoing NICHD R01-funded project that brings together both psychological and biological perspectives to understand how pregnancy stress impacts maternal/child outcomes. Knowledge gained by this proposed R03 study will specifically advance understanding about how pregnancy stress affects women's mental health and endocrine state to impact early caregiving and will help identify critical target points for prevention and intervention with the most at-risk women.