Fetal femur length of 66mm on ultrasound at 38 weeks gestation is generally on the short side. The average value for fetal femur length on ultrasound at 38 weeks gestation is 72 ± 4.3 mm. a femur length of 66 mm is slightly short. However, this value does not indicate that the fetal femur length is that long. Ultrasound examination has some deviation, and the result of each individual is different to a certain extent. The fetus inherits the short legs from its parents, so if the parents have short legs, the fetus may also have short legs. Fetal development is not judged solely on the basis of femur length. It is usually necessary to consider a number of parameters, such as biparietal diameter, abdominal circumference, limbs and so on, to comprehensively assess the development of the fetus. The baby will also continue to develop after birth, and it is possible to slowly improve the child’s height through acquired means. The femur 66mm at 38 weeks of pregnancy can be combined with other tests to determine whether the fetus is normal or not, you can follow the doctor’s advice, do not need to worry too much about it.