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 July 31, 2005, 35,082 women had contributed biological samples (blood and urine) for the NIEHS portion of the study; 13,000 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 100,000 women. At the current recruitment rate we anticipate 40,000 women with blood and urine samples collected at 17 weeks gestation to evaluate for environmental exposures by the end of 2005. During the past fiscal year, we completed a manuscript on issues related to urine storage and environmental exposures (phenols, phthalates, non-persistent pesticides). 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 were presented at a professional meeting in October 2004 and a manuscript is currently in preparation. 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 effects of a common environmental contaminant, probably phthalates.