Pathways to Teen Rapid Repeat Birth and Adverse Birth Outcomes ABSTRACT Rapid repeat birth (RRB; birth < 24 months of the first birth) among teen mothers heightens the risk for adverse birth outcomes. Infant mortality, very low birth weight (birth weight < 1500 grams), and pre-term birth are three times more common among second births to teens as compared to first births. The racial and socioeconomic disparities that increase the risk of teen parenthood widen among those who give birth a second time within two years. Investigators are increasingly focusing on differential exposure to adverse childhood experiences (ACEs; e.g., emotional, physical, or sexual abuse; exposure to domestic violence; substance abusing, mentally ill, or criminal household member; or separated/divorced parent) to explain health disparities. In this study, we will determine mechanisms affecting the incidence and timing of teen RRB, and its maternal and infant health outcomes. The study focuses on ACEs as a trigger launching a trajectory for teen birth and RRB. Specifically, we will 1) determine if adverse childhood experiences (ACE score) are associated with selected reproductive attitudes (e.g., ambivalence), behaviors (e.g., risky sexual behaviors and health related behaviors during pregnancy), and allostatic load among teen mothers; 2) delineate variation in the incidence and timing of RRB by adverse childhood experiences and determine whether this relationship is mediated by reproductive attitudes and behaviors; and 3) determine the relationship between ACE score and maternal/infant health outcomes and ascertain whether psychosocial (e.g., attitudinal and behavioral) and physiological mechanisms (e.g., allostatic load) mediate the associations between ACE score and adverse birth outcomes. The proposed study will use a multi-method design in a hospital-based longitudinal, multi-ethnic cohort study of 500 teen mothers following the birth of their first child. Participants will complete an initial assessment that includes attitudinal and behavioral measures, as well as an in-depth assessment battery to capture exposure and extent of ACEs. Dried blood spots will be used to obtain biomarkers of exposure to chronic stressors. Participants will be tracked for up to 18 months to determine if a second pregnancy occurs. This study is significant because teen RRB and its negative health outcomes are a public health problem, and current preventative efforts have had limited success. Findings from this study will elucidate reasons for heightened risk with a particular focus on pathways leading from stressors. The proposed project is innovative; it will be the first to examine the biopsychosocial pathways leading from adverse childhood experiences to teen RRB and adverse birth outcomes. The positive impacts of this work include information that will be used to develop an intervention for first-time teen mothers with the aim of preventing RRB and its adverse birth outcomes.