PGF and preeclampsia: The first clinical trial to use Elecsys immunoassays for the determination of sFlt-1 and PlGF in order to evaluate the sFlt-1/PlGF ratio for the prediction of PE in short-term (up to 4 weeks) was the PROGNOSIS (Prediction of short-term Outcome in Pregnant Women with Suspected Preeclampsia) study.