Effectiveness of Doppler Indices in Predicting Adverse Perinatal Outcomes in Early and Late-Onset FGR: Systematic Review

Background: Doppler velocimetry guides monitoring in fetal growth restriction (FGR), and the most informative index differ by early- vs late-onset disease. We aimed to evaluate Doppler indices to predict adverse perinatal outcomes in early- and late-onset FGR. Methods: We searched online databases and screened full-text original studies linking Doppler measures with perinatal outcomes in FGR. Data were extracted on design, sample size, FGR, onset definitions, Doppler markers, outcome composites, and predictive performance, AUC, sensitivity, and specificity. Findings were analyzed qualitatively, because thresholds and outcomes varied. Results: we include nine observational studies. Common markers were UA-PI, MCA-PI, uterine artery PI, and ratios; some studies assessed composite measures. Late-onset cohorts found moderate to high discrimination for selected predictors, whereas larger cohorts showed modest performance for UCR and CPR thresholds. Abnormal UA Doppler was more sensitive than low CPR for predicting SGA, with similar specificity. Early abnormal UA Doppler identified higher stillbirth risk but had low sensitivity. Conclusion: Doppler indices aid risk grouping in FGR, but accuracy varies by onset phenotype, marker choice, and outcome definition; we need standardized thresholds and outcome sets in practice.