When ultrasound is done during pregnancy, the PSV of middle cerebral artery blood flow should be between 2.5 and 4. In fact, it is not this value that determines the blood supply of the fetus, but the S/D ratio, which is a direct response to the blood supply of the fetus. Under normal circumstances, with the increase of gestational weeks, S value decreases, D value increases, near full-term, this value is not more than 3, there is no good treatment for this high value during pregnancy, which is to recommend oxygen, regular checkups, relaxation, and self-counting of fetal movements.