The models for sFlt-1 or sFlt-1/PIGF ratio as continuous had similar performance in terms of calibration and discrimination, indicating no significant advantage in using ratio values of sFlt-1 and PIGF biomarkers (as continuous) to using sFlt-1 only as a biomarker. This finding concurs with the results reported in the preeclampsia prediction literature [10, 16]. Here, PIGF is linked to preeclampsia.