Although primarily used in agriculture, pesticides have a wide range of applications, and there are many sources of public exposure to them. The levels of pesticide exposure in the general population are poorly understood in France and in most European countries. Measuring exposure using biomarkers has the advantage of accounting for all possible routes of exposure. Given the particular sensitivity of fetuses to toxins, assessing the exposure of pregnant women is a major public health issue. The Pélagie cohort included nearly 3,500 pregnant women in Brittany between 2002 and 2006. Urine samples were collected at the beginning of pregnancy, and chemical analyses of pesticides were performed on 546 urine samples. The objective was to assess the level and extent of pesticide exposure among pregnant women, particularly to herbicides in the triazine family—banned in France since late 2003 but still present in the environment—and to organophosphate insecticides used in both agricultural and non-agricultural settings. The results indicate the presence of traces of pesticides in the urine of the majority of pregnant women, with some molecules being persistent environmental degradation products of parent molecules. These pesticide residues are generally multiple, and their individual or combined impacts on the fetus and its development remain uncertain in the epidemiological literature. They will be evaluated shortly in the Pélagie cohort. (R.A.)