Aim of this prospective nonprofit study is to analyze the benefits of early onset pre eclampsia risk assessment in the 1st trimester (measuring biochemical markers [PIGF], blood pressure and Doppler ultrasound), and how the results can permit to modify or influence the course of the preeclampsia during the pregnancy. The investigators will also evaluate the potential use of the PIGF as a marker to improve the prenatal screening with the currently used nuchal translucency, serum Pregnancy-associated plasma protein A (PAPP-A) and free beta subunit of human chorionic gonadotropin (fBhCG) parameters.