PROJECT SUMMARY Adverse pregnancy outcomes (APOs), such as preterm birth and low birth weight, are a major, costly health problem[1, 2]. Compared to the United States overall, significantly higher rates of preterm birth exist in Puerto Rico, where nearly 11.4% of all births in 2017 are preterm. Rates of low birth weight in Puerto Rico are likewise much higher than the U.S. average. Evidence exists that exposure to Superfund chemicals contributes to APOs. Established in 2010, the Puerto Rico Testsite for Exploring Contamination Threats Center (PROTECT) uses a holistic system of research, training and stakeholder engagement to study transport, exposure, health impact and remediation of contaminants. The focus in this submission is to study the impact of specific mixtures of environmental contaminants on APOs. The set of mixtures selected for study are environmental agents with potential for adverse health effect in the prenatal period and are consistently found in PROTECT participants. The Human Subjects and Sampling Core (HSSC) provides a single point of contact to obtain data and biological and environmental samples linked to human subjects. For this renewal, the HSSC will maintain and enhance the infrastructure needed to recruit pregnant women from the northern karst region of Puerto Rico to participate in the program’s longitudinal research (Aim 1). The HSSC will build on the experience of partners from the University of Puerto Rico School of Public Health and the University of Georgia, who have recruited cohorts of pregnant women for diverse studies over the last decade. In the current funding period, HSSC formed and trained a team of nurses, physicians, support staff and graduate students that recruited and retained 1457 pregnant women with over 1280 followed until they completed pregnancy (including 1210 live births.) The intent of the proposed renewal is to recruit an additional 1000 participants, ultimately yielding a cohort of over 2,000 complete births. In addition to recruiting, the HSSC will systematically collect and share multiple sources of data. To acquire detailed information on potential predictors of APOs, the HSSC will conduct sequential interviews with study subjects, abstract medical records, and collect biological and environmental samples during pregnancy, delivery and postpartum (Aim 2). Because many of the projects have the same data or sample needs, a single systematic process for collection and sharing data and samples avoids duplication of effort and decreases the contact time with study subjects. This is a better use of time and available resources and reduces participant burden. The HSSC will process, archive and distribute samples to project investigators, and in collaboration with the Data Management and Analysis Core, maintain a repository of samples with an integrated database (Aim 3).