If you have had a Down’s syndrome baby before, you need to go to the doctor for a non-invasive DNA test or an amniocentesis test. If you have had a Down’s syndrome baby before, you need to consult a doctor in time for various tests, such as non-invasive DNA test, through which you can know the fetal chromosomal status of the fetus and determine whether there are symptoms of chromosomal abnormality, and you can also choose to carry out an amniocentesis test. In addition, various tests need to be conducted during pregnancy, and Down’s syndrome can be caused by a variety of factors, such as genetic factors, advanced age factors, and may also be related to normal lifestyle habits. Therefore, it is recommended to follow the doctor’s instructions to carry out NT test, Down’s syndrome test, 4D ultrasound and other tests during pregnancy.