4D ultrasound is one of the more important means of checking fetal growth and development during pregnancy and is usually performed between 18-24 weeks. 4D ultrasound is four-dimensional medical color ultrasound imaging, also known as real-time 3D. 4D ultrasound examination can mainly observe the growth and development of the fetus in multiple directions and angles, and conduct early detection of whether the fetus has abnormalities: 1. head examination: observe whether the fetal head outline is complete and whether there are abnormalities in brain tissue, such as hydrocephalus and anencephaly; 2. facial examination: check whether there are abnormalities in the five facial features of the fetus and whether there is cleft lip and palate. The examination of organs: to determine whether there is congenital heart malformation, whether there is abnormal kidney development such as polycystic kidney, hydronephrosis, etc., whether there is intestinal atresia, megacolon, visceral ectopia, etc.; 4. spine and limbs examination: to observe whether the spine is continuous, whether the limbs are well developed, etc.; 5. placenta and amniotic fluid examination: to check whether there is abnormal placenta and amniotic fluid through 4-dimensional ultrasound. 5. Placenta and amniotic fluid examination: the 4D ultrasound can be used to check whether there are any abnormalities in the placenta, whether there is too much or too little amniotic fluid, and whether the umbilical cord is round the neck. If the fetus stays in one position for a long time or is sleeping, the pregnant woman needs to walk around more or eat food such as chocolate to stimulate the fetus to move so that she can check the growth and development of the fetus in multiple directions and in a more comprehensive way. In addition, the 4D ultrasound has no radiation hazards, so it has no effect on the mother or the fetus, so you can be assured that the examination will be performed according to the doctor’s instructions.