Supplementary Material for: sFlt-1/PlGF ratio predicts serious outcomes in early-onset fetal growth restriction

Introduction: This study aimed to identify a cutoff value for the soluble fms-like tyrosine kinase-1 (sFlt-1)/placental growth factor (PlGF) ratio to predict adverse outcomes in early-onset fetal growth restriction (FGR). Methods: In this single-center, non-blinded, retrospective cohort study, maternal serum sFlt-1/PlGF ratios were measured at the time of early-onset FGR diagnosis (<34 weeks) using Roche Elecsys® assays. The optimal cutoff for predicting severe adverse outcomes within 2 weeks was determined using receiver operating characteristic analysis. Kaplan–Meier analysis assessed delivery probability, and Cox proportional hazards models evaluated factors associated with pregnancy continuation. Results: Among 332 patients, 61 (18.4%) delivered within 2 weeks due to worsening FGR. An sFlt-1/PlGF ratio ≥99.0 predicted adverse outcomes leading to an inability to continue the pregnancy, with 85.3% sensitivity and 91.5% specificity (AUC: 0.92). Women with ratios ≥99.0 had a significantly shorter time to delivery (P < 0.001). The ratio remained a significant predictor of adverse outcomes in both asymptomatic and preeclampsia-complicated FGR. Conclusion: The sFlt-1/PlGF ratio is a strong predictor of short-term adverse outcomes in early-onset FGR, aiding in risk stratification and clinical decision-making.