Description:This project is funded by the NIH Environmental influences on Child Health Outcomes (ECHO) program, and uses data from five cohorts: Healthy Start, Project Viva, Atlanta ECHO, Paneth Cohort, and PETALS. This project will generate new untargeted metabolomics profiling data at two time-points in pregnancy for all women in order to identify trimester-specific metabolomics signatures and longitudinal metabolomics trajectories associated with offspring birth size; identify the contribution of maternal sociodemographic and perinatal characteristics to the metabolomics signatures.