The femur length does not mean the legs are long, the femur length is related to the pregnancy week, you can’t judge by the femur length whether the legs are long when you grow up. Fetal femur length varies from week to week, for example, the average femur length at 20 weeks is 3.35±0.47 centimeters, and the average femur length at 38 weeks is 7.20±0.43 centimeters. If fetal femur length exceeds this range, it generally indicates that the fetus is developing well, but it is not certain that the fetus will grow up to be long-legged as well. Doctors can assess fetal weight based on femur length in combination with other test results. Femur length is not 100 percent accurate, and the test may be inaccurate when performed by different doctors. If the femur length is lower than the normal range, it is recommended to consult a doctor in time, and under the doctor’s guidance, improve the relevant examinations to clarify the cause of the disease and treat the symptoms.