Fasting is usually not required for Down screening alone, as long as you are careful not to eat too much greasy food before the test. Down screening is the abbreviation of prenatal screening for Down’s syndrome. By drawing venous blood and measuring the values of HCG, AFP and free estriol in the serum of the pregnant woman, combined with the weight, medical history and age of the pregnant woman, the risk of the fetus developing Down’s syndrome is calculated. With the current improvement in medical standards and the sophistication of serum separation techniques, the requirement for pregnant women to fast is no longer as stringent as before, as long as they avoid a high-fat diet. Of course, some doctors may still recommend fasting. Therefore, it is advisable to consult a doctor in a regular hospital before undergoing the Down screening test, so that you can make an appointment for the test and consult the relevant precautions to prepare in advance.