The doctor said it is late to do 4D ultrasound at 24 weeks of pregnancy, it may be because the best examination time is missed, it may also be related to the pregnant woman’s own situation, as follows: 1, miss the best examination time: you need to make an appointment in advance to do 4D ultrasound, now you are already 24 weeks pregnant, if you make a successful appointment, you may miss the best 4D ultrasound examination time, usually it is more suitable to do 4D ultrasound examination at 20-26 weeks of pregnancy. 2. Pregnant women’s own condition: For example, if they have undergone general ultrasound examination within a short period of time, they may be advised by the doctor that they should not undergo 4D ultrasound examination for the time being because there should be an interval between two ultrasound examinations in order not to cause adverse effects on the fetus. 4D ultrasound, also known as macroscopic ultrasound, is mainly to rule out any major and lethal malformations in the fetus. During the 22-24 weeks of pregnancy, the fetus is already well developed, and the ultrasound can reveal the presence of malformations in various organs. At this stage, there is more amniotic fluid in the uterus and the fetus can move freely, which is beneficial for the ultrasound doctor to conduct a comprehensive examination. If abnormalities are found in the 4D ultrasound, it is recommended to further consult with the prenatal diagnosis clinic to determine if appropriate treatment or termination of pregnancy should be carried out.