Pregnant women usually have a 4D ultrasound at 24-28 weeks. When the pregnancy week will reach 24 weeks, pregnant women should try to go to the hospital to make an appointment in advance, because the number of people doing 4D ultrasound is also relatively large, and the time of doing ultrasound is also different. If the fetus cooperates well, the ultrasound will be done faster, but if the fetus does not cooperate well, some parts of the ultrasound will not be seen clearly and the examination will be repeated. When you go to the hospital, bring as much information as possible about your previous examinations so that the doctor can compare them. When the gestational week reaches 24 weeks, the development of the fetus’ brain tissue, internal organs, limbs and the external appearance of the five senses has basically been completed. The first thing to do with 4D ultrasound is to make routine measurements and observations of the fetus’ development. The focus is to check whether the fetus has any congenital diseases, such as internal organ ectopia, congenital heart disease, limb agenesis, hydrocephalus, spina bifida, etc. 4D ultrasound can clearly show the five senses and fingers of the fetus, and can also screen for malformations in these areas, and can observe whether the placenta is positioned inferiorly. At 24 weeks of gestation, when the volume of amniotic fluid is also relatively high, it can serve as a good window for sound transmission, so that the fetal images can be displayed more clearly.