PROJECT SUMMARYThe prevalence of opioid use disorder (OUD) during pregnancy has increased by nearly 500% over the past 15years. While motivation for and compliance with OUD treatment during pregnancy is heightened up to 80% ofpostpartum individuals with OUD relapse to illicit opioid use within six months of childbirth. A growing body ofevidence indicates that in the general population positive social connectedness and strong social bonds areassociated with improved OUD recovery outcomes (e.g. reduced craving lower risk of relapse). Converselyloneliness and social isolation are significant predictors of opioid misuse and relapse particularly for women.Loneliness increases during transitional periods including from pregnancy to postpartum signaling increasedrisk for adverse recovery outcomes. Moreover relapse risk during the fourth trimester (i.e. the time from deliveryto postpartum week 12) may be compounded by unique postpartum stressors including postpartum depressionand anxiety sleep disturbances heightened need for pain management and caregiving-specific stress. Ouroverall goal is to understand the role of social connectedness in OUD-related recovery outcomes specificallyduring the postpartum fourth trimester an ideal inflection point with untapped potential. To achieve this goal wewill pursue three aims. The first two aims will utilize existing data (derived from DP2-HD105541; PI: Allen) from50 participants with OUD and 25 control participants who were followed from pregnancy through five monthspostpartum. Using ecological momentary assessments (EMA) paired with medical record data we will assesssocial connectedness and OUD-related recovery outcomes. We will evaluate differing theoretical models ofsocial connectedness in this population by testing the main and stress-buffering effects of social connectednesson recovery outcomes up to one year postpartum (Aim 1). Additionally we will characterize dynamic changes insocial connectedness across the fourth trimester and how patterns/changes relate to mothers recoveryoutcomes (Aim 2). Lastly we will complete key informant interviews with 30 participants from the targetpopulation to explore the feasibility acceptability and opportunities for intervention to enhance socialconnectedness to improve the treatment of OUD and prevent postpartum relapse (Aim 3). The results of thisstudy regardless of outcome will directly contribute to scientific knowledge on the role of social connectednessin postpartum OUD recovery. Moreover this work will allow for the identification of new intervention targetswhich will contribute to the development of novel high-impact relapse prevention treatments tailored to the fourthtrimester a unique inflection point with ample untapped opportunity. This will be directly impactful to the 80000-120000 women infants and families suffer the consequences of perinatal OUD every year.