The day before the non-invasive DNA precautions: non-invasive DNA test does not need fasting, pay attention to the examination time. 1. Non-invasive DNA test does not need fasting: non-invasive DNA test needs to extract the blood of pregnant women, when doing non-invasive DNA test, there is no need for fasting, pregnant women can ensure that the normal diet with it is good. 2. Pay attention to the examination time: non-invasive DNA prenatal examination can be carried out at 12 weeks to 26 weeks of pregnancy. If you want to take this test, you need to do it within the specified time, so that it will not affect the effect of the test, but also to improve the accuracy of the test. Before the non-invasive DNA test, the pregnant woman needs to sign an informed consent form, and she should understand the significance and process of the non-invasive DNA test. Whether the non-invasive DNA test is needed and whether there are any contraindications to the test need to be diagnosed and clarified by the obstetrician, and the pregnant woman should not decide on her own judgment.