Down’s syndrome screening can be done in the third month of pregnancy. The first screening is early screening, which is done between 11-14 weeks of pregnancy, or 3 months of pregnancy. The second screening is the mid-term screening, which requires the patient to be 16-20 weeks pregnant, that is, about 5 months pregnant. These 2 screening tests will help the patient to determine if the fetus is at risk for intellectual disorders such as Trisomy 21 and Trisomy 18. If the test is high risk, the patient will need to undergo further exclusion, such as non-invasive genetic testing or amniocentesis, for further confirmation. However, in clinical practice, the results of amniocentesis are the main criterion for further confirmation, so patients are advised to choose amniocentesis as much as possible.