Non-invasive DNA is a test for free genetic sequences in the blood of pregnant women, so fasting is generally not required to perform a non-invasive DNA test. About 5ml of venous blood is usually drawn from the pregnant woman and can be collected with a single blood collection tube. The genetic information of the fetus is then obtained through the examination of the genetic sequence, thus providing effective screening for the three major chromosomal disorders (Down’s syndrome, Edward’s syndrome, and Patau’s syndrome). There is no need to be nervous before the test, just maintain a normal routine, eat a light diet and avoid a high-fat diet. If a pregnant woman suffers from needle sickness or blood sickness, she should inform the medical staff who will help with the test in advance so that appropriate measures can be taken to prevent it. If a pregnant woman is obese, of advanced age, pregnant with two or more children, or less than 12 weeks pregnant, the accuracy of the test results may be affected. Non-invasive DNA prenatal testing has a high accuracy rate in diagnosing the presence of the three major chromosomal disorders in the fetus. If a pregnant woman is at high risk for disease screening, she should follow medical advice for further differential diagnosis.