Growing research indicates that the brain undergoes dramatic changes across the peripartum period, and that heightened emotional reactivity, particularly to infant emotions, emerges at some point during this time. Research on brain function across pregnancy has been limited by concerns about possible risks of neuroimaging and relatively small, cross-sectional samples. Consequently, our knowledge of neural trajectories across this period is inferred from studies of postpartum women and non-human animal research, rather than within-person longitudinal studies of dynamic change. This study will be among the first longitudinal, multimodal projectsto examine trajectories of brain function and behaviorin pregnant woman. We have developed safe and tolerable methods for measuring neural, physiological, and behavioral responses to highly salient auditory and visual emotional stimuli. We will apply these methods to chart trajectories of reactivity to infant distress cues from pregnancy to postpartum with the aim to better understand the changes in emotional reactivity. Participants will visit the lab at three time points (approximately 20 weeks gestation [T1], 34 weeks gestation [T2], and 8 weeks postpartum [T3]). At each assessment, women will complete an infant face matching task in which they viewinfant emotional faces and shapes with and without interspersed infant crying audio. At the neural level, event-related potentials in response to distressed infant faces will be used to measure emotional reactivity. At the physiological level, we will examine heart rate variability in the cry vs. no-cry conditions as an indicator of availabilityemotional demands. Behaviorally, we will examine reaction time when matching infant distressed faces in the cry vs. no cry condition as an indicatorof effects of distress cues on performance.