Longitudinal Arterial and Venous Doppler Changes in Late-Onset Fetal Growth Restriction

OBJECTIVE: This study aimed to evaluate longitudinal changes in arterial and venous Doppler parameters in late-onset fetal growth restriction and to investigate their association with NICU admission. STUDY DESIGN: This prospective cohort study included singleton pregnancies diagnosed with LO-FGR at or beyond 32 weeks of gestation and followed at a tertiary perinatology center between August 2025 and February 2026. Serial Doppler assessments included measurements of the umbilical artery (UA), the middle cerebral artery (MCA), and the ductus venosus (DV). DV waveform-derived parameters, including pulsatility index for veins (PIV), preload index (PLI), peak velocity index for veins (PVIV), S/a ratio, and time-averaged maximum velocity (TAmax), were evaluated together with arterial Doppler indices and the cerebroplacental ratio (CPR). Neonatal intensive care unit (NICU) admission was used as the primary outcome. RESULTS: Fifty-two pregnancies with LO-FGR were included. Longitudinal evaluation showed a significant decrease in MCA PI between the first and second examinations (p=0.026). In contrast, no significant changes were observed in DV Doppler parameters, including DV PIV, PLI, PVIV, S/a ratio, and TAmax. UA Doppler indices and CPR also remained stable over time. NICU admission occurred in 21.2% of neonates. Longitudinal changes in DV PIV and CPR were not significantly associated with NICU admission. In multivariable analysis, weekly change in CPR showed a borderline association with NICU admission (adjusted OR 0.04, 95% CI 0.002–1.08, p=0.056). CONCLUSION: In LO-FGR, arterial Doppler parameters, particularly MCA PI, may show longitudinal change, whereas venous Doppler parameters remained relatively stable. These findings suggest that fetal adaptation in LO-FGR primarily manifests in the arterial circulation.