There are not many people with high risk of trisomy 21, and only a very few women will have it. The presence of high risk of trisomy 21 can be considered as a higher probability of having a Down’s syndrome baby, so it is important to actively undergo the Down’s syndrome test. The high risk of trisomy 21 indicates a chromosomal abnormality. Generally, the chance of chromosomal abnormality is relatively small, so the number of people with high risk of trisomy 21 is relatively small, and only a very few women will have it. Usually women are tested for Down’s syndrome at 15 to 20 weeks of pregnancy. If the test is for high risk of trisomy 21, it also indicates that the fetus is at risk of developing trisomy 21. Since the Down’s syndrome test is not 100% accurate, further testing can be done, either by amniocentesis or non-invasive DNA. If the diagnosis of high risk of trisomy 21 is confirmed, it is usually necessary to abandon the fetus. It is important for women to take regular pregnancy tests during pregnancy and to avoid over-exertion.