A 4D ultrasound is performed on a pregnant woman to rule out malformations in the fetus, and the best time for this test is 22-24 weeks of pregnancy. During the 22-24 weeks of pregnancy, the growth and developmental state of the fetus tends to stabilize, and the fetus is large and easy to observe, so you can observe the vital status of the fetus and check for developmental malformations during this period of time. The 4D ultrasound mainly observes the fetal heart, fetal movement and the coordination of facial and body movements. This time is chosen as there is more amniotic fluid and clear ultrasound at 22-24 weeks of pregnancy. Pregnant women should take care to eat breakfast to replenish energy and also exercise moderately to promote fetal movement in the uterus to facilitate the doctor’s all-round observation of the fetus during the 4D ultrasound examination of the fetus.