Usually, the best time for a pregnant woman to have a 4D ultrasound is between 20 and 24 weeks of pregnancy. 4D ultrasound is a kind of ultrasound examination, through which you can get a better understanding of the structure and dynamics of the organs of the organism, as well as understand the development of the embryo in the uterine cavity of the pregnant woman and the shape of the body, and other aspects, but also to check the existence of congenital malformations and anomalies. It is generally not recommended to check 4D ultrasound too early, because it takes time for the embryo to develop into a fetus in the mother’s body, and for a fetus with a small gestational age, all the body systems are not yet mature, so it is not able to check the specific condition of the fetus. Pregnant women are advised to take regular ultrasound tests under the guidance of a doctor in order to ascertain the specific growth status of the fetus and to ensure that the fetus develops in a normal and healthy manner.