It is perfectly possible to have a 4D ultrasound at 6 months, which means that the best time to have a 4D ultrasound is between 24-28 weeks after pregnancy. Before the 6th month of pregnancy, which is the early stage of pregnancy, ultrasound or general color ultrasound can be done to observe the development of the fetus. However, after the 6th month of pregnancy, the development of the fetus has been basically completed, including the development of the head, face, limbs and internal organs, and the 4D ultrasound can observe whether the development of the fetus is normal, including the development of the head, face, digestive system, urinary system, cardiovascular system and limbs. In the sixth month of pregnancy, the amount of amniotic fluid is also relatively high. At this time, the amniotic fluid can be used as a good sound transmission window to observe the baby’s every movement in the pregnant mother’s belly, and can clearly show the baby’s facial state and expression, as well as the baby’s movement posture. If the baby is doing yawning, tongue out and other cute movements can be observed. Therefore, it is best for pregnant mothers to go for a 4D ultrasound between 6 and 7 months to observe the development of the fetus and the amount of amniotic fluid, as well as the position of the placenta, which can rule out abnormal development of the fetus.