T21 high risk refers to high risk of trisomy 21 and T means triplet. If the fetus is found to be at high risk for trisomy 21 during the Down’s syndrome screening, it means that the fetus has a very high probability of having Down’s syndrome, and the pregnant mother needs to follow the doctor’s instructions for further non-invasive DNA screening or amniocentesis to confirm the diagnosis. The clinical manifestations of Down’s syndrome include mental retardation, widened eye spacing, low nasal bridge and many other malformations of the body and internal organs, and low life skills after birth. The first thing you need to do is to make sure that your baby is diagnosed with Down’s syndrome and that you terminate the pregnancy in time.