4D ultrasound results are mainly based on the development of various fetal indicators, including the biparietal diameter, head circumference, abdominal circumference, femur length, amniotic fluid value and so on. 1. Biparietal diameter: mainly refers to the length between the right and left sides of the fetus’s head. The length of the biparietal diameter of the fetus is about 4.88±0.58 CM at this time when you are almost 4~5 months old with 4D ultrasound. 2. Head circumference: the head circumference of the fetus is also the length of a circle around the head along the head, in about 4~5 months of pregnancy, the head circumference of the fetus is about 56-58mm. 3. Femur length: this is the length of the fetus’s thighs. If the ultrasound is done at 4-5 months, the femur length of the fetus is about 2-3CM, and it can grow 1CM every month. 4. Depth of amniotic fluid: In 4-5 months of pregnancy when doing 4D, the depth of amniotic fluid is 3-7cm. If the data observed through 4D is not normal, it is considered that the embryo development is delayed or too fast, and you need to consult a doctor in time and analyze the reason under the doctor’s guidance.