sFlt-1 to PlGF ratio cut-offs to predict adverse pregnancy outcomes in early-onset FGR and SGA: a prospective observational study.

This is a prospective, observational study, conducted in a tertiary referral hospital. We enrolled 175 singleton pregnancies with estimated foetal weight below the 10th centile between 20 + 0 and 31 + 6 weeks. Placental growth factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1) and fetoplacental circulation were assessed at the time of diagnosis. Receiver operating characteristic curves were used to assess the performance of sFlt-1/PlGF for predicting adverse perinatal outcomes (APO). The optimal cut-offs to predict each adverse outcome were calculated and the resulting areas under the curve (AUC) were compared to those calculated from the cut-off points of 38, 85 and 110. The need for delivery at <30 and <34 weeks and APO were the main outcome measures. The optimal cut-off points to predict APO, delivery <30 and <34 weeks were 24.9, 116.7 and 97.5, respectively. None of them proved to be superior to 38, 85 or 110 for predicting any adverse pregnancy outcome. Impact Statement Soluble fms-like tyrosine kinase-1 (sFlt-1) and placental growth factor (PlGF) are biomarkers of placental dysfunction. High sFlt-1/PlGF values predict adverse perinatal outcomes in preeclampsia (PE). No specific thresholds have been described to identify early-onset foetal growth restriction (FGR) and small for gestational age (SGA) foetuses at higher risk of adverse outcomes. This study describes these specific cut-offs and compares their predictive capacity to those described for PE. The sFlt-1/PlGF cut-off points of 38, 85 and 110 might be useful for ruling out the occurrence of APO and the need for elective delivery at <30 and at <34 weeks from the moment of diagnosis in early-onset FGR and SGA. These cut-offs could aid Doppler studies in the distinction between FGR and SGA.