The Norwegian Mother and Child study is a cohort study of pregnant women and their children in Norway. NIEHS is contributing to this effort by creating of a biological specimen repository to evaluate environmental exposures and health effects to pregnant women and their unborn children. As of Aug 31, 2004, 22,710 women had contributed biological samples (blood and urine) for the NIEHS portion of the study; 10,000 women were enrolled this fiscal year. These samples have been collected at 41 hospitals across Norway including urban centers and the Arctic regions. The enrollment target is 50,000 women. At the current recruitment rate we anticipate 30,000 women with blood and urine samples collected at 17 weeks gestation to evaluate for environmental exposures. During the past fiscal year, we resolved problems associated with sample shipment and handling. Working with CDC, we identified the optimal means to prevent bacterial contamination of urine samples while still maintaining the analytes of future interest (phenols, phthalates, non-persistent pesticides, arsenic, mercury). These data will be of use to other investigators in large cohort studies and a manuscript is in preparation. In collaboration with Norwegian investigators, we are implementing a quality assurance experiment and protocol to assess storage conditions for a variety of parameters. This will take ~2 years to complete. Results of the initial quality assurance measures will be presented at a professional meeting in October 2004. We are currently designing a study to use the NIEHS samples and link to the questionnaire data from the mother and the Medical Birth Registry data to assess health