4D is best done at 18-24 weeks of pregnancy.
4D is generally used for macrosomia screening, which is like taking a photo, and may look for cleft lip, spina bifida, brain, kidney, heart, and bone dysplasia. It is usually better to have a 4D ultrasound within 18-24 weeks.
At this time, the fetus has been molded and is better developed in all aspects. The muscles on the face and body, as well as the fat under the skin have developed, and the amniotic fluid is more appropriate at this time, so the fetus can be seen more completely under the ultrasound.
If it takes longer than that, the space in the uterine cavity becomes smaller and smaller, and sometimes the fetus is easily squeezed, making it difficult to find a good position to view the fetus.
Before the 4D ultrasound examination, pregnant women should pay attention to the time period of the baby’s activities, and it is best to choose the time when the fetal movement is more active for the examination, so that it is conducive to see the specific situation of the fetus clearly.