A high risk of trisomy 21 means that the fetus is more likely to be born with trisomy 21 than pregnant women of the same age, but it does not mean that the fetus necessarily has a chromosomal abnormality. Trisomy 21 is a common chromosomal disorder in which the child may suffer from mental retardation, developmental delay and physical deformities. The purpose of Down’s syndrome screening is to detect the risk of trisomy 21 in the fetus, and if the risk is high, amniocentesis can be performed between 22 and 28 weeks of gestation. However, amniocentesis carries certain risks during pregnancy, so some families who do not want to take the risk can also opt for non-invasive genetic screening. Although non-invasive genetic screening does not give a definite result, it can further clarify the risk level and if it is still high risk after the screening, it can be reconsidered for amniocentesis. After amniocentesis, if the fetus is confirmed to have trisomy 21, termination of pregnancy is usually recommended to avoid a huge financial burden on the patient’s family and a detrimental effect on the affected child itself.