Materials and Methods: This cross-sectional analytical study was conducted at a high-risk pregnancy clinic of Kowsar Medical Center between October 2025 and February 2026 on 85 singleton pregnancies at 24–36 weeks" gestation. Fetuses with structural or chromosomal anomalies and pregnancies requiring urgent termination were excluded. Standard fetal biometry and Doppler ultrasound of the umbilical artery (UA), middle cerebral artery (MCA), and SVC were performed. IUGR was defined according to ISUOG criteria and stratified into mild, moderate, and severe subgroups. Statistical analysis was performed using SPSS 26, with P < 0.05 considered significant.

Results: The mean maternal age and gestational age were 30 years and 33 weeks, respectively. Most IUGR cases were moderate to severe. Reduced SVC Doppler resistance indices were observed in 58% of IUGR fetuses and were significantly associated with growth restriction (P < 0.05). In contrast, the SVC-to-Aorta diameter ratio did not differ significantly between IUGR and normally grown fetuses. Functional SVC Doppler parameters demonstrated stronger discriminatory value than static vessel size measurements.

Conclusions: SVC Doppler indices offer meaningful complementary information regarding fetal hemodynamic redistribution in IUGR. Decreased SVC resistance reflects central circulatory adaptation to placental insufficiency. Integration of venous Doppler assessment with established arterial indices may improve fetal surveillance, although larger prospective studies are needed to confirm clinical utility.