The reasons for failing the Down’s syndrome screening may include poor accuracy, too old, and the actual condition of the pregnant woman does not match. 1. Accuracy is not high: most people can not pass the Down’s syndrome screening, not the fetus really has Down’s syndrome, but the accuracy of the Down’s syndrome screening is not high, pregnant women need to do amniocentesis and other tests, there is no abnormality means that the results of the previous Down’s syndrome screening results are wrong. 2. too old: most people can not pass the Down’s syndrome screening may be related to the age of the pregnant woman, generally speaking, pregnant women aged 35 years old or older is not suitable for Down’s syndrome screening, more than 35 years old pregnant women to do Down’s syndrome screening failure rate is high. 3. Pregnant women’s actual situation does not match: Down’s screening most people can not pass may be pregnant women to provide the height, weight, gestational week and other circumstances and the actual inconsistency, resulting in Down’s screening results inaccurate. After the pregnant women can not pass the Down’s syndrome screening, you can continue the relevant programs under the guidance of the doctor, do not be anxious.