High risk of Down syndrome is considered to be caused by fetal chromosomal abnormalities. There are several causes of high risk of Down syndrome: i. Advanced age. When the pregnant woman is older than 35 weeks of age, the risk of the fetus having Down syndrome will increase substantially, and the older the age, the higher the risk. Second, poor lifestyle. Long-term staying up late, alcohol abuse, smoking, and stressful work life can also cause fetal chromosomal abnormalities. Since the screening rate of general Down screening is only about 60%, there is no need to be too nervous when the result of Down screening is high risk. However, you should follow the doctor’s instructions and choose non-invasive prenatal DNA screening or amniocentesis to confirm the diagnosis according to the age and risk cut-off value of the pregnant woman.