Project Summary/Abstract. In this renewal application, we will advance the success of the Environmental Influences on Child Health Outcomes program that seeks to “enhance the health of children for generations to come” as one of the Pregnancy and Pediatric Cohort Study Sites. Since 2009, the New Hampshire Birth Cohort Study, a rural prospective molecular epidemiology study, has accrued data and biologic samples on pregnant people and their children with a goal of 6,000 dyads (including 1,005 new pregnancies and 2,800 children consented into ECHO) by August 2023. Data and biospecimens are being leveraged for nearly 100 Concept Proposals (each with one or more manuscripts), including Opportunity and Infrastructure awards to early career investigators and COVID-19 supplements, and with more in the pipeline. Already, 7,440 of our cohort’s biospecimens have been committed to 11 ECHO-Wide laboratory analyses led by our Dartmouth team and other investigators. This includes the ECHO Genome Wide Association Study to which most participants are contributing DNA samples. Non-DNA biologic samples available or being shipped to the ECHO Biorepository include urine, toenails, hair, blood, placenta, meconium, human milk, stool, and teeth. We took part in ECHO program leadership, committees and working groups, designing and sharing protocols, and creating instructional videos and participant feedback materials. We addressed the urgent call for health equity, fostered workforce diversity, and prioritized public health crises, including time sensitive evaluation of SARS- CoV-2 on our most vulnerable populations. We are committed to strengthening these efforts in the next phase. We responded to congressional and agency stakeholders as well as health care providers and families and plan to elevate this engagement moving forward to ensure diverse perspectives and inclusion in our cohort and impact of our work. We will recruit 1,500 additional pregnant people, enlist their conceiving partner, enroll them into a preconception cohort if planning another child and follow children previously accrued into the cohort and newly born in this study phase. We will adhere to the ECHO Cohort Protocol, rely on the program’s REDCap Central database and single IRB. We will continue to capitalize on ECHO’s unprecedented data and samples from diverse populations across the USA, along with Dartmouth’s robust infrastructure and interdisciplinary expertise. Specifically, we will (1) address rural health inequities by characterizing the rural exposome and its impact on child health outcomes, (2) determine the early drivers of lower and upper airway disease and other outcomes and the mediating role of the developing microbiome using specialized measures of exposures (e.g., dietary nutrient-toxicant composition) and outcomes (e.g., respiratory infections and vaccine response), and (3) investigate the influence of inter-pregnancy adiposity and factors of the conceiving partner on child growth...