The value of this test is not very meaningful, and it is only meaningful to refer to the femur length of the large sample statistics of various national races. Indicators of fetal growth and development include biparietal diameter, femur, chest circumference, abdominal circumference and head circumference, and many other indicators, and in the process of prenatal examination, it is also a combination of a number of data results to make a comprehensive judgment. In general, the difference between the fetal biparietal diameter and femur length is about 2 centimeters, but it is not an absolute fixed value and has a certain range of fluctuation. Biparietal diameter minus femur length of more than 2 centimeters suggests that there is a possibility of fetal leg shortening, but it is not absolute, if the development of the biparietal diameter of the development of a larger, it may also lead to the difference between the two differences in the difference between the value of the larger. Therefore, if the difference between the biparietal diameter and the femur length is more than 2 centimeters, it is recommended to review the ultrasound to evaluate the development of the fetus during the pregnancy checkup. In addition, the short femur can only indicate that the fetus is slower during pregnancy, and does not represent the height of the fetus after birth, so you can take moderate calcium supplements during pregnancy and do not exert yourself.