Under normal circumstances, it is more suitable for women to have 4D ultrasound in the middle of pregnancy, that is, between 22 and 26 weeks of pregnancy. Because the development of the fetus during this period is moderate and the amniotic fluid is more, it can see the growth and development of the fetus more comprehensively, such as whether there are malformations of the head and face, cleft lip and palate, whether the spine is normal and the development of the limbs, and it can also observe whether there is cervical bypass of the placenta and the amount of amniotic fluid and other conditions. Women in the four-dimensional ultrasound, can be more three-dimensional to see clearly, the development of the fetus is in line with the gestational week, and is mainly to observe whether there is the presence of malformations of the body surface, for the mid-pregnancy B ultrasound macro-anomalies, is a better screening program. After pregnancy not only need to do four-dimensional ultrasound to check the development of the fetus, but also pay attention to blood tests, do electrocardiograms, in order to pay attention to prevent the existence of pregnancy complications.