The purpose of this contract is to support analysis of human biological specimens for urinary biomarkers of oxidative stress, including 8-iso-prostaglandin F2?, 2,3-dinor-5,6-dihydro-15-F2t-isoprostane (primary F2-isoprostane metabolite), and prostaglandin F2?. Samples are analyzed via gas chromatographic/negative ion chemical ionization mass spectrometric (GC/NICI?MS) methods (see Milne et al. 2007) using appropriate quality control procedures. Analytes will be examined in relation to biomarkers of environmental chemical exposure and in relation to adverse outcomes of pregnancy.