Calculating the baby’s weight according to the biparietal diameter is usually done by multiplying the checked biparietal diameter data by 900 and then subtracting 5200, but it is not entirely accurate, and the measurement will usually be different from the actual one. According to the above calculation, if the measured biparietal diameter of the fetus is 9.2 centimeters, the weight of the fetus will be about 3080 grams, that is, about 6 pounds 2 taels. In addition to calculating the weight based on the biparietal diameter, it is also necessary to make a comprehensive assessment based on the chest circumference, abdominal circumference and head circumference. Generally, the weight of the fetus can also be estimated clinically by combining the uterine height and abdominal circumference of the pregnant woman. However, it should be noted that fetal weight can only be accurately measured after delivery, and measurement during pregnancy is for reference only.