There is no precise range for the normal range of middle cerebral artery PI values, as it varies with the week of gestation. Overall, the highest values are found at 28 weeks of gestation and then gradually decrease with each week of gestation. Moreover, the increase or decrease of the middle cerebral artery PI value varies in significance from one gestational week to another. In general, an increase in the value in the middle of pregnancy may be associated with fetal anemia; a decrease in the value in the late pregnancy may be associated with fetal hypoxia. When evaluating the fetal condition, it should be combined with the fetal umbilical artery flow index and other comprehensive judgments. It is advisable to go to the obstetrics and gynecology department of the local public tertiary hospital for relevant examinations, which can clarify the growth and development of the fetus, as well as make a clear determination of the cause and carry out appropriate treatment according to the specific examination results.