Arterial and Venous Doppler Parameters in Fetal Growth Restriction: A Comparative Evaluation of Early- and Late-Onset...

Objective: To evaluate and compare fetal arterial and venous Doppler parameters in early-onset (EO) and late-onset (LO) fetal growth restriction (FGR), and to assess their performance within the study cohort and their association with composite adverse neonatal outcome (CANO). Methods: This prospective observational cohort study included 184 singleton pregnancies between 24 and 37 weeks of gestation, comprising 91 FGR cases and 93 appropriate-for-gestational-age controls. FGR was defined according to Delphi consensus criteria and classified as EO-FGR (<32 weeks) or LO-FGR (≥32 weeks). All fetuses underwent standardized Doppler assessment of the umbilical artery (UA), middle cerebral artery (MCA), uterine artery (UtA), and ductus venosus (DV). The cerebroplacental ratio (CPR) was calculated. Multivariable logistic regression models were constructed separately for EO-FGR and LO-FGR. Classification performance was evaluated using receiver operating characteristic analysis. CANO was defined as at least one of the following: 5-min Apgar score <7, respiratory distress syndrome, neonatal intensive care unit admission, or preterm birth. Results: In both EO-FGR and LO-FGR, UA PI values were significantly higher, whereas MCA PI and CPR were significantly lower than in controls. CPR demonstrated the highest discriminative performance among arterial parameters in both subgroups. DV Doppler indices were not significantly different in EO-FGR. In LO-FGR, DV S-wave and v-wave velocities were independently associated with FGR. No significant associations were observed between Doppler parameters and CANO in subgroup analyses. Conclusions: Arterial Doppler parameters, particularly CPR, showed consistent alterations in both EO- and LO-FGR. The contribution of venous Doppler parameters differed according to clinical subtype, with additional value observed in LO-FGR.