It is a more important indicator of fetal development during pregnancy. It is more accurately measured around 10-12 weeks of gestation and can reflect the size of the developing fetus and whether it conforms to the gestational week. If the length of the parietal-rump diameter of pregnant women with regular menstrual cycles deviates from the normal value, we should pay attention to guiding pregnant women to carry out a balanced diet and control their weight and blood sugar to avoid having a huge baby.