4D pregnancy means that pregnant women need to have a 4D ultrasound examination. 4D ultrasound examination is a relatively advanced examination method in ultrasound examination. In this examination method, the development of the fetus seen during the examination can be recorded on a CD. Both the ultrasonographer and the pregnant woman herself or her family can observe the baby’s development and the fetal movement function through the CD. Since the examination results are more accurate and reliable, it is now widely used in obstetrics for fetal development and can make a more accurate diagnosis of the fetal surface development, internal organ development and motor function development. The best time to have a 4D ultrasound examination is between 22-26 weeks of pregnancy, and the examination can be scheduled 2-4 weeks in advance.