Formula for calculating fetal weight by biparietal diameter

During pregnancy, you can estimate the weight of the fetus by measuring the biparietal diameter of the fetus. There is a formula, the weight of the fetus is about 900× the biparietal diameter value, and then-5200, this is only an estimate, can not be sure that the fetus is born this weight, there is a certain probability of error, this is also a normal phenomenon. Fetal weight is influenced by many factors, such as maternal nutrition, and possibly placental function. If the pregnant woman has diabetes, then if the blood sugar control is not good, it may cause the fetus to show excessive growth, showing macrosomia, and may also show fetal growth restriction, causing the fetus to show small.