PROJECT SUMMARY/ABSTRACT Exposure to adverse childhood experiences (ACEs) is linked to deleterious, life-long, and intergenerational consequences for biobehavioral health. Children of mothers exposed to ACEs show altered stress physiology and have over 5 times greater odds of developing an emotional or mental disturbance, with risks emerging early in infancy as dysregulated stress reactivity, poor developmental outcomes, and negative emotionality. A key biological process underlying the intergenerational transmission of maternal ACEs (mACEs) on offspring is dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, driven in part by methylation of glucocorticoid receptor (GR)-related genes that alter offspring cortisol reactivity. Specifically, mACEs are linked to altered infant methylation of NR3C1 and FKBP5, though directionality of effects has been inconsistent. In addition to mACEs, maternal adult attachment orientation (mAttach) is another critical but underexplored environmental factor implicated in modulation of the physiological stress response and transmission of adversity across generations. Secure attachment is associated with biobehavioral resilience following childhood adversity, and moderates the link between ACEs and adverse health outcomes. Attachment orientation is linked to epigenetic modification of both NR3C1 and FKBP5, and secure attachment is associated with better adaptive functioning for mothers (regulated stress physiology, fewer physical/mental health problems) and for offspring (secure attachment, social-emotional development). To date, limited prospective information exists on the functional implications of GR-related methylation for infant stress reactivity, and no studies have examined methylation of both NR3C1 and FKBP5 during pregnancy in relation to GR-related methylation and acute stress reactivity in infants. The proposed study will use a prospective longitudinal design to examine if 1) mACEs and mAttach predict methylation of maternal and infant glucocorticoid-related genes during pregnancy and postpartum (Aims 1 and 2); and 2) whether GR-related methylation explains the effects of mACEs and mAttach on maternal and infant cortisol reactivity (Aim 3). A sample of 100 mothers will be recruited (30-35 weeks gestation, oversampled for ACEs). mACEs and mAttach will be self-reported at baseline as key predictors and baseline methylation of NR3C1 and FKBP5 will be measured from saliva. Infant methylation of NR3C1 and FKBP5 will be measured from saliva at 6-weeks postpartum. Maternal and infant salivary cortisol reactivity to an acute stressor will be measured at 16-weeks postpartum. The proposed research will help clarify how adversity is transmitted intergenerationally, linking genes, experiences, and developmental timing to differential lifelong outcomes and intergenerational health. This work is innovative and a critical step toward our long-term goal of reducing the harms of ACES by identifying novel, precise...