If the non-invasive DNA test suggests an excess of chromosomes, there is a possibility that it belongs to a chromosomal chimera and further amniocentesis is required. Non-invasive DNA testing is generally done to check for disorders of the three pairs of chromosomes 13, 18 and 21. The accuracy of testing for these three pairs of chromosomes is relatively high, but the accuracy of testing for sex chromosomes is not particularly high. Non-invasive DNA testing suggests that the sex chromosomes are on the high side and that there are two chromosome systems in the body. That is, there is a chimera of chromosomes, which is a situation that requires further amniocentesis. Non-invasive DNA test sex chromosome bias, it is recommended that prenatal diagnostic counseling, follow the doctor’s instructions for amniocentesis, amniocentesis for chromosome examination is more comprehensive, and more accurate.