Preeclampsia (PE) is a major obstetric complication with short- and long-term consequences for the mother and the fetus. Early screening tools to reduce its mortality and morbidity, as well as to prevent the life-threatening consequences are needed. Thus, the detection of women at risk of suffering PE is key to apply preventive and treatment strategies. Recently, the maternal contribution to PE based on defective decidualization that prevents the establishment of a functional maternal-fetal interface has been evidenced. The main objective of this study is to identify molecular markers or aberrant maternal-fetal cell types that can be detected early in the development of the disease in chorionic villi collected during gestational weeks 9 to 14. Chorionic villi will be collected from women who have a recommendation for aneuploidy testing. The remaining fragment will be used for this study.