If the Down’s syndrome screening test shows a critical risk, the next step must be further testing, either by non-invasive DNA or directly by amniocentesis. If the results of the non-invasive DNA test are low risk, then the amniocentesis may not be done. If the amniocentesis is done for prenatal diagnosis. If there is a fetal developmental abnormality or a chromosomal abnormality, it is determined whether to terminate the pregnancy depending on the extent of the abnormality. Non-invasive DNA alone is also a prenatal screening and is not a final diagnosis. Therefore, if Down’s syndrome screening is a critical risk, the most accurate screening method is amniocentesis, but amniocentesis carries certain risks and requires informed choice.