BACKGROUND: Little is known about healthcare use and costs for commercially insured infants in the first year of life following a Neonatal Intensive Care Unit (NICU) hospitalization. PURPOSE: To evaluate healthcare utilization and costs in the 12-months after a neonatal hospitalization among commercially insured infants, comparing infants with and without medically complex conditions. METHODS: This retrospective, cross-sectional, cohort study uses data from the IBM MarketScan Commercial database (2015-2019). The cohort included infants with and without medically complex conditions, hospitalized at birth in the NICU, discharged alive, and had 12-months continuous coverage. The primary outcomes are healthcare utilization (i.e., hospital readmissions, emergency department (ED) visits, and primary care and specialty outpatient visits) and out-of-pocket (OOP) costs. RESULTS: The analysis included 23,940 infants, of which 84% resided in urban areas, 48% were born term (>
37 weeks) and 43% had a medically complex diagnosis. Medically complex infants exhibited higher rates of readmissions, ED visits, specialist utilization, and specialty services. Average OOP costs for medically complex infants was 893, compared to 73 for noncomplex infants. Almost half (48%) of the cohort had costs that exceeded 00 in the first year of life. IMPLICATIONS FOR PRACTICE AND RESEARCH: This study provides insights into the financial implications of post-NICU care for infants. Findings underscore the importance of considering medical complexity over gestational age when understanding healthcare use and spending patterns. Policymakers, healthcare providers, and families can use these insights to address the financial challenges associated with caring for infants with complex medical conditions beyond the NICU.