There is no need for an empty stomach for the 4D. 4D generally refers to 4D ultrasound examination, which is a relatively common examination method in the middle of pregnancy. This method is generally through the 3D ultrasound image plus the dimension parameter of time, which can show the dynamics of the fetus in real time, as well as discovering the growth and development of various organs of the fetus to exclude whether there is any developmental abnormality. Generally for 4D ultrasound need to be examined at 20 weeks to 28 weeks of pregnancy, usually do not need to fasting, eating will not affect the results of the examination. Ultrasound during pregnancy does not require fasting except for fasting to look at the liver and gallbladder. It is recommended to perfect the prenatal checkups at all stages of pregnancy, and if there is any abnormality, it is recommended to seek medical attention in time.