Four-dimensional ultrasound is usually a mandatory examination, while regular general ultrasound examination should be done to rule out fetal malformation and other conditions. Four-dimensional ultrasound, also known as dynamic three-dimensional ultrasound, is usually performed during the 24th to 28th week of pregnancy, which is the best time to show the physical condition of the fetus in three dimensions, and to see the development of the face and organs of the fetus, etc. It can also observe the fetus in real time, and diagnose whether there is any abnormality of the development of the fetus at an early stage. Therefore, 4D is usually a necessary examination. Ordinary color ultrasound observes the fetus less clearly than 4D ultrasound, and at the same time, it can only detect large structural malformations of the fetus. In addition, pregnant women should have more rest, maintain a happy mood, supplement a lot of nutrients and go to the hospital for regular checkups in their daily life.