Serum sFlt-1/PlGF Ratio as an Early Predictor of Preeclampsia in High-Risk Pregnancies between 20–28 Weeks of Gestation: A Prospective Observational Study

Abstract

Background: Preeclampsia (PE) remains a leading contributor to maternal and perinatal morbidity, particularly in low- and middle-income settings. Imbalance of circulating angiogenic factors precedes the clinical onset of disease, and the ratio of soluble fms-like tyrosine kinase-1 (sFlt-1) to placental growth factor (PlGF) has emerged as a promising early biomarker. The present study evaluated the diagnostic performance of the serum sFlt-1/PlGF ratio measured between 20 and 28 weeks of gestation for the prediction of subsequent PE in high-risk pregnancies. Methods: A prospective observational study was conducted over 12 months in a tertiary care obstetric unit. One hundred and fifty pregnant women with one or more risk factors for PE were enrolled between 20 and 28 weeks of gestation, of whom 145 completed follow-up to delivery. Maternal serum sFlt-1 and PlGF concentrations were quantified by automated electrochemiluminescence immunoassay, and the ratio was calculated. Participants were followed until delivery for the development of PE as defined by the International Society for the Study of Hypertension in Pregnancy criteria. Diagnostic accuracy was assessed using receiver operating characteristic (ROC) curve analysis. Results: Preeclampsia developed in 39 of 145 women (26.9%). The median sFlt-1/PlGF ratio at 20–28 weeks was significantly higher in the PE group than in the non-PE group (60.4 [IQR 38.7–94.6] versus 11.2 [IQR 6.8–18.4]; p < 0.001). The area under the ROC curve for the ratio was 0.892 (95% CI 0.838–0.946). At a cut-off value of 38, the ratio yielded a sensitivity of 79.5%, specificity of 84.0%, positive predictive value of 64.6% and negative predictive value of 91.8% for the prediction of PE. Adverse perinatal outcomes including preterm birth, foetal growth restriction and neonatal intensive care admission were significantly more frequent in the PE group. Conclusion: The serum sFlt-1/PlGF ratio measured at 20–28 weeks of gestation is a robust early predictor of subsequent preeclampsia in high-risk pregnancies, with high diagnostic accuracy and an excellent negative predictive value. Incorporation of this biomarker into routine antenatal surveillance of high-risk women may permit earlier risk stratification, intensified surveillance and timely interventions to reduce maternal-foetal morbidity.