Fetal weight can be calculated by fetal biparietal diameter, maternal uterine height and abdominal circumference, etc. However, the results of the measurements may also have some deviation and are only for reference. 1. Calculation based on fetal biparietal diameter: It is recommended to measure the fetal biparietal diameter through ultrasound examination. Calculate the weight of the fetus according to the biparietal diameter, i.e., fetal weight (g) = biparietal diameter (cm) x 900-5200. 2. Uterine height-abdominal circumference method: The obstetrician will calculate the fetal weight by measuring the uterine height and abdominal circumference of the pregnant woman, i.e., fetal weight (g) = uterine height (cm) × abdominal circumference (cm) + 200. During pregnancy, any method of calculating fetal weight is only a general assessment with a certain degree of error, but it is also necessary to do regular and proper maternity checkups to detect abnormalities and deal with them as early as possible.