Abstract: Fetal middle cerebral artery (MCA) blood supply to the brain hemisphere is the most abundant blood vessel, which has more important clinical value in reflecting the dynamic changes in fetal cerebral circulation and blood oxygen status. In normal pregnancy, fetal brain development gradually improved with the increase of the gestational age, and the reference curve of blood flow parameters is characterized by a typical parabolic pattern for the color Doppler ultrasonography of fetal MCA. There is a certain correlation in high-risk pregnancies between the perinatal adverse pregnancy outcomes and placental deficiency or vascular resistance increase. Fetal MCA hemodynamics will show an abnormal change when internal and external environment changes such as hypoxia. The various blood flow signal indicators of the color Doppler ultrasonography of fetal MAC also will show an abnormal trend. Color Doppler ultrasound used to detect fetal MCA blood flow index is safe, non-invasive, convenient and reproducible to mother and fetal, can be used to reflect a series of pathophysiological changes in the fetal, and become a significant clinical tool in the evaluation of fetal growth status and intrauterine safety in recent years.

Key words: Fetus, Middle cerebral artery, Ultrasonography, prenatal, Ultrasonography, Doppler, color, Fetal growth retardation, Fetal distress