Friends, secondary prevention is the identification of severe congenital defects in the fetus through screening during pregnancy and prenatal diagnosis, and the reduction or avoidance of the birth of children with major defects through early detection and early intervention. Today, we begin with a compendium and summary of prenatal screening, in the hope that you can more objectively recognize the importance of prenatal screening. Prenatal screening is customarily referred to as Down syndrome screening. Of course, in addition to assessing the risk of fetal Down syndrome (hereinafter referred to as Down’s), prenatal screening can also assess the risk of fetal trisomy 18 and open neural tube defects. Below, we will mainly focus on some of the problems encountered in Down’s syndrome screening, which we believe is also a topic of interest to expectant parents. A closer look at Down syndrome Down syndrome, also known as trisomy 21 and formerly known as congenital stupidity, is the earliest chromosomal disorder identified in humans, with an incidence of about 1:1000 to 1:600 in live births, and the higher the age of the mother, the higher the incidence. It occurs primarily as a result of a nondisjunction of chromosome 21 in the germ cells of one of the spouses during meiosis to form gametes (mature egg and sperm), or during mitosis of a fertilized egg, and the presence of an extra chromosome 21 in the somatic cells of the embryo. The most significant damage is that it leads to severe mental retardation and cardiovascular malformations in the affected children, with approximately 40% of the children having congenital heart disease. The intelligence quotient (IQ) of the affected children is mostly 25-60, which is only 1/4 to 1/2 of that of their normal peers.The disease cannot be treated, but prenatal diagnosis and selective abortion can be performed during pregnancy. There is an annual increase of about 26,600 cases of Down’s syndrome in China, with an average of one case of Down’s syndrome being born in 20 minutes, and there are already one million people with Down’s syndrome in China. The average life expectancy of Down’s syndrome patients is around 45 years old. According to the current economic level, the cost of raising a Down’s syndrome patient is around$600,000, which imposes a heavy financial and mental burden on society and families. It is for this reason that the United Nations General Assembly has designated March 21st of each year as World Down Syndrome Day, to call attention to these children and their families. The “New OSCAR” Strategy for Prenatal Screening in Early Pregnancy In 2002, the British Fetal Medicine Foundation (BFMF) proposed the “One-stop Clinic of Risk Assessment (OSCAR)”, which is a one-stop clinic for the 11th trimester of early pregnancy to assess the risk of Down’s Syndrome. In 2002, the British Fetal Medicine Foundation introduced the “One Stop Clinic of Risk Assessment (OSCAR)”, which is a screening program for the risk of Down’s syndrome and other common chromosomal aneuploidies in the fetus, using a combination of ultrasound measurement of fetal nuchal translucency (NT) and immunological testing of the mother’s serum for the concentrations of PAPP-A and free-βHCG. The detection rate for Down’s fetus can reach more than 95% and can be accomplished in a single test between 11 weeks and 13 weeks and 6 days of early pregnancy, but OSCAR cannot screen for most fetuses with open neural tube defects and certain common aneuploidy disorders (e.g., 47,XXY and 47,XYY syndromes), nor can it screen for the risk of preeclampsia that may occur in pregnant women. In 2014, the Genetic Diagnostic Center of the First People’s Hospital of Yunnan Province, on the basis of OSCAR screening, proposed a new program of one-stop prenatal screening in early pregnancy with the addition of serological testing indexes and noninvasive DNA testing, which is capable of screening for Down syndrome and other common chromosomal aneuploidies of the fetus in a single examination for pregnant women in the first trimester of pregnancy from 11 weeks to 13 weeks and 6 days, open neural tube defects, severe congenital heart disease and Open neural tube defects, open neural tube defects, severe congenital heart disease and major structural anomalies, and pre-eclampsia in pregnant women are all covered by one test, referred to as the New OSCAR. The detection rate for Down syndrome is 99%. It also detects about 60% of severe congenital heart disease and about 60% of pregnant women at risk of developing preeclampsia. At the same time, “New OSCAR” has introduced commercial insurance, for non-invasive DNA testing of high-risk single-fetus pregnant women will be covered by the insurance company to cover the prenatal diagnostic costs of 2,500 yuan, for missed screening of Down’s syndrome fetus will be reimbursed by the insurance company to pay 400,000 yuan of the cost. Friends, having a healthy baby is the good wish of every couple. In fact, no matter what kind of prenatal screening technology and screening strategy we choose, the ultimate goal is to guarantee the comprehensiveness and accuracy of the screening, reduce the risk of missed screenings, avoid the birth of diseased fetuses, and reduce the burden of disease on the society and the family at the lowest possible cost. Although the Down’s syndrome screening service in our province has been extended to many county-level maternal and child health care institutions, due to the limitations of economic development, medical services and publicity and education in some areas, the screening coverage rate is less than 25%, and many pregnant women in remote areas do not know about or will not take the initiative to undergo Down’s syndrome screening, which has led to the tragedy of giving birth to Down’s syndrome babies. We hope that this issue of the topic can play a role in publicizing and educating, so that more pregnant women and friends correctly understand Down’s syndrome screening and take the initiative to carry out Down’s syndrome screening.