In human pregnancy, abnormal placental hemodynamics likely contributes to the etiology of early-onset preeclampsia and fetal intrauterine growth-restriction. The mouse is increasingly being deployed to study normal and abnormal mammalian placental development yet the placental hemodynamics in normal pregnancy in mice is currently unknown. We used ultrasound biomicroscopy to non-invasively image and record Doppler blood velocity waveforms from the maternal and embryonic placental circulations in mice throughout gestation. In the uterine artery, peak systolic velocity (PSV) increased significantly from 23±2 (SEM) to 59±3 cm/s and end-diastolic velocity (EDV) increased from 7±1 to 28±2 cm/s in non-pregnant versus full-term females so that the uterine arterial Resistance Index (RI) decreased from 0.70±0.02 to 0.53±0.02. Velocities in the maternal arterial canal in the placenta were low and nearly steady and increased from 0.9±0.03 at embryonic day 10.5 (E10.5) to 2.4±0.07 cm/s at E18.5. PSV in the umbilical artery increased steadily from 0.8±0.1 at E8.5 to 15±0.6 cm/s at E18.5 whereas PSV in the vitelline artery increased from 0.6±0.1 at E8.5 to 4±0.2 cm/s at E13.5, and then remained stable till term. In the umbilical artery, the EDV detection rate was 0% E14.5 and 94% at E18.5 and the RI decreased from 1 to 0.82±0.01 over this interval. We conclude that ultrasound biomicroscopy can be used to monitor placental hemodynamics during pregnancy in mice. These results provide novel information concerning the development of the vitelline and placental circulations in mice, and reveal strong similarities in placental hemodynamics between mice and humans.