The high risk of Down’s syndrome screening is mainly considered to be caused by fetal chromosomal abnormalities, the causes of fetal chromosomal abnormalities include: first, the advanced age of pregnant women, the risk of fetal chromosomal abnormalities will rise sharply if the age of pregnant women is greater than 35 weeks old; second, environmental pollution, if long-term living in a polluted environment, such as chemical pollution, pesticide pollution, long-term exposure to radiation, etc. can cause fetal chromosomal All these reasons may cause chromosomal abnormalities in the fetus, resulting in high risk of Down’s syndrome screening. The high risk of Down’s syndrome screening does not mean that the fetus is definitely a child with Down’s syndrome. Depending on the age of the pregnant woman and the risk value of Down’s syndrome screening, further non-invasive DNA screening or amniocentesis should be performed according to the doctor’s recommendation to confirm the diagnosis.