The 4D ultrasound chart, or 4D ultrasound, is recommended to be performed at 20-24 weeks of pregnancy, with the exact time varying according to the physical condition of each pregnant woman. At 20-24 weeks of pregnancy, the development of fetal organs and bones is basically completed, and 4D ultrasound can be performed at this time to clearly observe the real-time dynamic image of the fetus through 4D ultrasound, and check whether the fetus is healthy. Through 4D ultrasound, doctors mainly check the head, face (lips, eye sockets, nostrils, upper lip, etc.), chest (heart, lungs and other organs), limbs, spine (morphology, composition, and skin integrity), etc. of the fetus, to see if there are any problems such as cleft lip and palate, spina bifida, and congenital organic diseases. In addition, you should pay attention to rest a few days before the 4D ultrasound examination to ensure sufficient sleep, and you can eat some appropriate food before conducting the examination, which can increase the excitement of the fetus and help the doctor observe the development of the fetus from more directions and angles.