How is Down syndrome screening performed?

Down syndrome screening is a prenatal examination method primarily used to assess the risk of fetal chromosomal abnormalities such as Down syndrome. The screening process is as follows: Down syndrome screening is usually performed during the second trimester (15–20 weeks of pregnancy). The pregnant woman needs to come to the hospital fasting, where a venous blood sample will be taken to measure biochemical markers in the serum, including alpha-fetoprotein (AFP), unconjugated estriol (uE3), and human chorionic gonadotropin (hCG). At the same time, the physician will combine the pregnant woman's age, weight, gestational age, and other personal information with these results, using specialized software to calculate the risk coefficient for Down syndrome. The screening results are typically categorized as high risk or low risk. A high-risk result indicates a higher likelihood of fetal abnormality and requires further prenatal diagnosis, such as amniocentesis, to confirm the diagnosis. The entire screening process is simple, quick, and poses no harm to either the pregnant woman or the fetus. It is an important measure for preventing the birth of infants with Down syndrome. Pregnant women should undergo Down syndrome screening on schedule and follow up with additional examinations and treatments as advised by their physicians.