As the standard of living continues to improve, eugenics is becoming more and more important. Down’s syndrome screening is a test that calculates the risk of a fetus developing the congenital disorders trisomy 21, trisomy 18, and trisomy 11 by measuring biochemical markers in the vein blood of a pregnant woman. With an accuracy rate of about 50 percent, these screenings are only an assessment of risk, not a diagnosis. Blood is drawn between 15 weeks and 20 plus 6 weeks. It is recommended that families with the necessary conditions can directly do non-invasive dna screening, the accuracy rate is 99%, direct extraction of venous blood can be detected, direct sequencing of maternal venous plasma DNA fragments containing fetal free DNA for in-depth sequencing, from which to get the genetic information of the fetus, and to determine the presence of chromosomal aneuploidy disease, without fasting, the time of blood sampling in the period of 12 weeks to 26 weeks. It greatly reduces the rate of birth of diseased children. Amniocentesis is also a diagnostic tool for high-risk pregnancies.