PGF and preeclampsia: In the present study, we created a multicenter study to investigate the ability of midtrimester serum levels of sFlt-1, PlGF, and sFlt-1/PlGF ratio to identify women at high risk for development of preeclampsia and to determine whether the use of sFlt-1/PlGF ratio was superior to the use of individual biomarkers sFlt-1 and PlGF in the prediction of preeclampsia.