Introduction: Vascular modifications mechanism in pregnancy with intrauterine growth restriction (IUGR) by placental defect is unknown. The objective of this study was to monitor and quantify uteroplacental perfusion during pregnancy in a RCIU rats model by Doppler (DUS) and contrast-enhanced ultrasound (CEUS). Materials and Methods: Thirty-six pregnant rats were randomized in three groups : control (1), hyperthermia 40℃ (2), and 41℃ (3). At gestational day (GD) 18 and 19, an hyperthemic stage (30 minutes) by increasing body temperature was performed for groups 2 (40℃) and 3 (41℃). DUS study was performed strictly after each hyperthermic stage. CEUS was performed on GD19 and GD20. Histological analysis of all placentas was performed after cesarian done after the last CEUS study. Weight birth of all fetuses was recorded. Results: Fetus' weight was significantly higher for group 1 compared to groups 2 and 3 (p < 0.02). The weight from group 3 fetuses was significant lower than this from fetuses from group 2 (p < 0.01). No significant difference was show for the DUS study. For CEUS study, a significant difference was noted between group 1 vs. 2 and 3 at G19 and G20. Discussion: IUGR model by hyperthermia showed a significant correlation between fetal weight birth and maternal body temperature. This IUGR is associated with a high fetal morbi-mortality with placental damage. Vascular modifications are more tissue destruction than structural modifications.