There are two measures for high risk of Down’s syndrome screening, as follows: 1. Amniocentesis: fetus cells in amniotic fluid are taken for karyotyping to make a clear diagnosis, which is usually carried out within 18-20 weeks, with simple operation, higher success rate, lower miscarriage rate and more reliable karyotyping results; 2. Non-invasive Fetal DNA Testing: for people with high risk of Down’s syndrome, the detection rate can be up to 99%. If the non-invasive fetal DNA test is high risk, the risk of Down’s syndrome is high, and amniocentesis is needed to further clarify the diagnosis.