It is mainly used to detect chromosome abnormality, which is generally used for prenatal diagnosis. Especially if there is a high risk of Down's syndrome, or the age is over 35 years old or nt color ultrasound is greater than 3 mm, it is recommended to make further prenatal diagnosis, and you can choose to do non-invasive DNA or amniocentesis.
Non-invasive DNA is now being tested in the gene company, which is a test item to extract venous blood from the mother's arm. But amniocentesis is through the mother's stomach, with a puncture needle to extract the child's amniotic fluid, to detect whether there are chromosomal abnormalities. There are advantages and disadvantages between the two.