PROJECT SUMMARY / ABSTRACT A comprehensive assessment of early exposures requires a multidimensional assessment of the exposome, including community-level environmental factors (such as air pollution), chemical exposures (such as endocrine disruptors), social factors (cultural and family context), and the genome and its responses to the environment (inherited epigenome, genomic expression, and the proteome). The Utah Children’s Project (UCP) has been the Utah site contributing to the ECHO Cohort consortium for 7 years. The UCP follows the exposure and outcome status of up to 2 children and at least 1 biological parent in 493 family units as well as enrolls couples planning pregnancy and pregnant people. In the UG3 Phase (the first two years), preconception and pregnancy enrollments will continue during the development of the cohort-wide preconception protocol in partnership with the other consortium sites. The UCP will also continue with retention and follow-up of families previously enrolled. Exposure assessment during the preconception and pregnancy periods is a specialized site focus area. In the UH3 Phase, preconception and pregnancy enrollments will continue with particular emphasis on Utah families from underrepresented minority populations (eg, Native Hawaiian or Other Pacific Islander, Hispanic), with a goal of up to 600 new enrollments with implementation of all aspects of the ECHO 3.0 protocol while maintaining a historically high cohort retention. Research questions to be investigated include (1) the relationship between subfertility, maternal metabolic status, fertility treatment, breastfeeding, and asthma in offspring, (2) the relationship between indoor air quality and perinatal outcomes, and (3) longitudinal preconception exposome mixtures and perinatal outcomes. A process-related aim is to re- enroll and retain at least 95% of currently enrolled children throughout the UG3 Phase, and 90% through the UH3 phase while implementing the ECHO 3.0 protocol with high fidelity and response rates.