Four-dimensional ultrasound must be done during pregnancy, the purpose of four-dimensional ultrasound examination is to exclude fetal organ development malformation. Because in the middle of pregnancy baby growth and development of various organs is basically perfect, and at this time the amount of amniotic fluid is large, so it is suitable for ultrasound doctors to carry out screening of fetal organ development abnormalities, it is generally recommended to carry out fetal four-dimensional ultrasound examination at about 24 weeks of pregnancy. If there are abnormalities in the baby’s development, it depends on the severity of the condition, the degree of harm to the fetus and mother, and serious lethal malformations require induction of labor. If the baby’s developmental abnormalities are only minor, the baby can be kept in labor for observation to see if the disease develops or returns later in life, and if there are no major special circumstances, the baby can wait until after delivery for intervention or treatment.