PROJECT SUMMARY The objective of this research project is to determine if indicators of adipose tissue development and metabolism are candidate biomarkers to identify preterm infants at risk of childhood obesity and cardiometabolic abnormalities. Infants born moderately preterm, between 32- and 36-weeks of gestational age, have 20% higher odds of obesity and cardiometabolic disease in adulthood compared with those born at term. Moderate preterm birth accounts for 8% of all births, or approximately 300,000 children born in the United States each year. Factors that may contribute to obesity risk among preterm infants include developmental re- programming due to perinatal exposure to maternal obesity and diabetes. Preliminary data shows that moderate preterm infants of mothers with diabetes have greater in-hospital growth over an average of 9 days compared with infants of non-diabetic mothers, after adjustment for gestational age, sex, and race. Accelerated growth in these infants may be due to alterations in the development, metabolism, and localization of adipose tissue. In a prospective cohort of moderately preterm infants, the aims of this project are: To determine the effect of maternal obesity and gestational diabetes on the development of adiposity at term corrected age and its association with adipose tissue metabolism biomarkers at birth (Aim 1) and to identify the role of early body composition assessments by magnetic resonance imaging and adipose tissue metabolism biomarkers at birth in predicting early childhood growth and development of adiposity and cardiometabolic abnormalities at age 2 years (Aim 2). Identification of these perinatal biomarkers is critical in the ability to risk-stratify infants at heightened risk of obesity and cardiometabolic abnormalities, and for the future development of interventions to optimize healthy growth and reduce obesity among preterm infants. Dr. Buck is a neonatologist whose long-term goal is to lead independent research examining perinatal risks that influence growth and development among preterm infants. The career development plan for this proposal builds upon Dr. Buck's prior training in epidemiology and clinical research methods through graduate-level coursework and mentored training in longitudinal study design, advanced biostatistical methods, biomarker and body composition assessment, and clinical trial study conduction. Dr. Buck has assembled a strong, committed team of mentors and advisors with expertise in infant nutrition, pediatric endocrinology, perinatal epidemiology, and biostatistics to help guide her successful transition to becoming an independent investigator, optimizing healthy growth and development of preterm infants and minimizing the development of obesity and cardiometabolic abnormalities in this vulnerable population.