Fetal body organs are not yet fully developed at 4 months, it is generally not recommended for pregnant women to undergo 4D ultrasound examination at this time, which may not be able to clearly determine whether there are developmental abnormalities in the fetus, and the results obtained will not be accurate enough. Four-dimensional color ultrasound examination belongs to the large screening examination, usually carried out in 20-24 weeks of pregnancy, mainly through the ultrasound examination to diagnose whether there are obvious malformations in the fetus, such as heart ventricular septal defect, partial loss of limbs, cleft lip and palate, abdominal wall cleft, hydrocephalus, anencephaly, spina bifida, cardiac anomalies, and malformations of the urinary system, and so on. The 4D ultrasound examination can not only see the development of the fetus, but also understand the physical condition of the pregnant woman. If 4D ultrasound is performed at 4 months, there may be missed diagnosis because some organs of the fetus are not yet fully developed. In addition, Down’s syndrome screening is also required at 4 months of pregnancy, which can effectively avoid the birth of children with Down’s syndrome. During pregnancy, pregnant women should pay attention to stay away from radiation, avoid toxic and harmful gas stimulation, and be on time for maternity checkups. During pregnancy, you should also pay attention to rest, avoid exertion, and maintain a happy mood, so as to ensure the normal growth and development of the fetus.