PROJECT SUMMARY Caring for hospitalized infants requires a comprehensive pain control program aimed at reducing and preventing pain. While opioids are commonly used when an infant undergoes a painful procedure, opioids can increase the risk of short- and long-term morbidity. The duration and type of opioids used for hospitalized infants varies widely between institutions and such wide variations could impact early childhood development and overall healthcare utilization. In this study, we will create a novel clinical and developmental dataset by merging the Pediatric Health Information System (PHIS) and the California Perinatal Quality Care Collaborative (CPQCC). This merged dataset will be the first large retrospective, multi-center cohort representing diverse populations of critically ill, hospitalized infants linking their in-hospital data with long-term neurodevelopmental outcomes. Using this novel dataset, we will (1) identify variations in opioid use associated with neurodevelopmental disability and long-term resource utilization for high-risk infants, (2) quantify cumulative opioid dosing received associated with neurodevelopmental disability for high-risk infants, and (3) quantify differences in healthcare utilization and costs associated with high vs. low opioid use among high-risk infants. The expected outcome is a comprehensive understanding of the variations in opioid use for high-risk infants and its impact on neurodevelopment and healthcare utilization. Results will lead to interventions for hospitalized infants aimed at minimizing variation in pain control and will also inform policymakers of a previously unrecognized infant population in need of increased resources to improve clinical and developmental outcomes.