Evaluation of Utero-placental and Fetal Hemodynamic Parameters Throughout Gestation in Pregnant Mice Using High-Frequency Ultrasound

Throughout gestation, changes in maternal and fetal Doppler parameters in pregnant mice, similar to those obtained in human fetuses, were detected using high-frequency ultrasound with a 55-MHz linear probe. In the uterine arteries (UtA), fetal umbilical artery (UA) and fetal ductus venosus (DV) peak systolic velocity increased (UtA, p = 0.04; UA, p = 0.0004; DV, p = 0.02), end-diastolic velocity increased (UtA, p < 0.001; UA, p < 0.0001; DV, p = 0.01) and resistance index decreased (UtA, p = 0.0004; UA, p = 0.0001; DV, p = 0.04) toward the end of pregnancy. In the middle cerebral and carotid arteries, end diastolic velocity increased (p = 0.02 and p < 0.0001) and resistance index decreased (both vessels, p < 0.0001). There was a reduction in the pulsatile pattern in the umbilical vein (p < 0.05). The increased velocities and reduced resistance index suggest a progressive increment in blood flow to the fetal mouse toward the end of pregnancy. Fetal and utero-placental vascular parameters in CD-1 mice can be reliably evaluated using high-frequency ultrasound.