4D, or four-dimensional ultrasound, is a must. 4D ultrasound can diagnose fetal heart disease as well as malformations, etc. It is usually done between 22 and 26 weeks of pregnancy. Four-dimensional ultrasound is a must-do examination during pregnancy because it can diagnose whether the fetus has heart disease, and four-dimensional ultrasound can also diagnose whether the fetus has deformities, such as facial deformities, short limb deformities, and syndactyly. In addition, 4D ultrasound can also check the nervous system of the fetus, such as anencephaly, hydrocephalus, etc. It can also check the digestive system, the urinary system, and the pregnant woman is whether there is too much amniotic fluid or amniotic fluid is too little. Pregnant women must do ultrasound during pregnancy, and it is recommended that pregnant women follow the doctor’s instructions to carry out obstetric examinations on time to avoid abnormal development of the fetus. If the four-dimensional ultrasound examination of fetal development problems, pregnant women should follow the doctor’s advice to choose specific measures to solve the problem.