Calculation of fetal weight is often estimated by ultrasound biparietal diameter, femur, abdominal circumference, but also through the uterine height and abdominal circumference, of which the most commonly used biparietal diameter estimation, the formula is 900 × biparietal diameter (cm) – 5200 = fetal weight (g). 1. Estimated by biparietal diameter: the formula is 900×biparietal diameter (cm)-5200=fetal weight (g), such as biparietal diameter of 90mm, the weight of the fetus is about 900×90 (cm)-5200=2900 (g) or so. 2. Estimated by fetal long bones: the formula is 747.42×femur length (cm)-2232.56=fetal weight (g), such as femur length 7.0cm, fetal weight is about 747.42×7-2232.56=2999.38 (g). 3. Estimated by fetal abdominal circumference: the formula is 171.48×abdominal circumference (cm)-2686.60=fetal weight (g), such as fetal abdominal circumference of 35cm, fetal weight is about 171.48×35-2686.60=3315.2 (g) or so. 4. Estimated by uterine height and abdominal circumference: the formula is uterine base height (cm) × abdominal circumference (cm) ± 200 = fetal weight (g), such as the uterine height of 35cm, abdominal circumference of 100cm, fetal weight of about 100 × 35 ± 200 (g) or so. No matter which parameter is used, there may be some difference between the estimated weight and the actual weight of the fetus. It is recommended to have a regular prenatal checkup during pregnancy, consult with a specialist for guidance, and pay attention to balanced nutrition in order to avoid fetal growth restriction or the occurrence of macrosomia.