Nowadays, many pregnant women are willing to do a more comprehensive examination between 22-26 weeks of pregnancy, that is, the 4D ultrasound examination. The 4D ultrasound is a dynamic 3D ultrasound, which is more three-dimensional and clearer, so the price is also slightly higher. The 4D ultrasound is able to surface imaging, such as fetal cleft lip and palate, limb development malformation, meningeal bulge, spina bifida, abdominal wall bifida and other congenital malformations, can be more clearly detected, so now many pregnant mothers will choose this examination. Another advantage is that it is possible to observe the fetus’ three-dimensional movement like a camera, so that the fetus can be displayed more comprehensively, truly and clearly in the womb.