4D is recommended to be performed at 24-28 weeks of gestation. It is important to do it on time, otherwise you may miss the best time for a major abnormality. The so-called 4D ultrasound can understand the development of the fetus in the womb in a clearer and more three-dimensional way, and the most prominent feature is that it can show the child’s appearance like a “portrait”, and even record some subtle activities of the baby in the womb, so the cost is more expensive than the ordinary ultrasound, but in fact, the resolution is not much different from that of 3D. However, in fact, the resolution of the ultrasound is not very different from that of 3D. The 4D ultrasound is mainly used for fetal organs detoxification examination: cleft lip, spina bifida, anencephaly, congenital heart malformation, etc. It is a very important examination, and the ultrasound has no effect on the baby whether it is 3D or 4D, but it should be emphasized that even the 4D ultrasound cannot detect all malformations. For pregnant women with high risk factors it should be combined with other tests such as Down screening, non-invasive DNA or even amniocentesis results. It is important to have regular maternity checkups throughout pregnancy, avoid strenuous exercise, and especially for medication intake always use medication under medical supervision. Ultrasound examinations too early or too late are inappropriate. About five ultrasounds are usually needed throughout pregnancy, and ultrasound examinations do not affect the growth and development of the baby.