4D ultrasound can be done at 23 weeks of pregnancy, and the suitable time for 4D ultrasound examination is generally 22-26 weeks of pregnancy, which can help screen fetal malformations. In addition to observing the growth and development of fetal organs, 4D ultrasound is mostly used to diagnose fetal malformations, such as cleft lip and palate, anencephaly, microcephaly, intestinal atresia, congenital heart disease and other malformations. The sensitivity, specificity and accuracy of the test are high. At 23 weeks of pregnancy, the fetal limbs and organs are basically developed, the amniotic fluid volume is moderate, and the fetal size is moderate, so it is suitable for fetal abnormality screening through 4D ultrasound to clarify whether the fetus is healthy. Beyond this gestational week, the fetus will be too big and the limbs will overlap, which will affect the ultrasound imaging and the screening effect will be poor. If the fetus is too small, some of the organs are not fully developed and this operation is not suitable. However, it should be noted that pregnant women should choose the ultrasound department of a regular public hospital for fetal 4D ultrasound examination in order to obtain a more reliable diagnostic basis. In addition, she should strengthen her health care during pregnancy and have regular obstetric checkups to monitor the growth and development of the fetus and identify any abnormalities in time. Pregnant women should strengthen nutrition and rest in their daily life, keep their mood comfortable and calm, and avoid straining for the benefit of pregnancy health.