The national biomonitoring program, implemented by Santé publique France (formerly the Institut de veille sanitaire), includes a perinatal component based on a subsample of pregnant women included in the biological component of the ELFE cohort (French Longitudinal Study from Early Childhood). The objective of this component is to estimate the exposure of pregnant women to certain pollutants present in the environment, particularly organic pollutants, and to quantify, if possible, the determinants of these exposure levels. This estimation is based on the measurement of biomarkers in biological samples collected in maternity wards from women who gave birth in mainland France in 2011. Volume I of the report presents the levels of exposure to bisphenol A, phthalates, and pesticides measured in urine, as well as the determinants of these exposure levels. It also presents serum concentrations of dioxins, furans, polychlorinated biphenyls (PCBs), brominated flame retardants, and perfluorinated compounds measured in a subsample of pregnant women included in Elfe. Any temporal and geographical variations in exposure levels to these organic pollutants were studied by comparing them with the results of previous studies conducted in France and abroad. The perinatal component of the national biomonitoring program made it possible to describe, for the first time, the exposure of French pregnant women to certain environmental organic pollutants and to quantify, where possible, the determinants of these exposure levels.