The normal range of femur length of 30 weeks fetus is 5.77-6.24cm. As fetal femur length is affected by many factors, such as: genetic factors, nutrition, measurement errors, etc.. Therefore, there are differences in the femur length of each fetus. Clinically, it is normal for the difference between the value of the fetal examination and the actual time of pregnancy to be within 1-2 weeks. Therefore, as long as the fetal femur length is within the normal value, it mostly does not need special treatment. Fetal femur length cannot be measured solely during pregnancy, but also needs to be combined with fetal biparietal diameter, head circumference, abdominal circumference and other indicators to determine the developmental situation. During pregnancy, you need to pay more attention to timely replenishment of sufficient nutrients, which can help promote fetal growth and development, and also need to take regular obstetric examinations to monitor the development indicators of the fetus.