Noninvasive refers to noninvasive DNA testing. The presence of chromosome 22 increased test results, relatively accurate, but can not completely exclude false-positive cases. Non-invasive DNA testing refers to fetal DNA sequencing by drawing maternal peripheral blood, which can assist in determining whether the fetus has a chromosomal disorder. If there is an increase in chromosome 22, the test result is generally accurate, and termination of pregnancy may be necessary, and further amniocentesis is recommended to clarify the diagnosis. If the test is performed too early, the test results may be affected to some extent and the accuracy may be reduced, which is an unexpected situation and is relatively rare. It is necessary for pregnant women to try to choose the test at 12-22⁺⁶ weeks of pregnancy, which can provide a strong supporting basis for clinical diagnosis and treatment.