Analysis of normal values for fetal biparietal diameter and femur length at 36 weeks With the continuous development of medical technology, fetal abdominal ultrasound examination has become one of the important means for pregnant women to prevent pregnancy complications. The normal value analysis of the biparietal diameter and femoral length of the fetus at 36 weeks is very critical for pregnant women and doctors. The following will cover fetal development, the significance of ultrasound and other aspects.