Before mid-pregnancy, short femur length is a normal phenomenon, because the development of various organs of the fetus at this time is not consistent, so there will be this kind of femur and other organs of the ratio is not consistent, to the second half of pregnancy will slowly return to normal. In addition, it has a lot to do with genetic factors, if both parents have short legs, then the baby’s legs may also be short. However, if the shortness of the femur is still serious in the second trimester, we should pay attention to it, because it may be caused by fetal malformation.