Why should I have prenatal screening? It is the common wish of every family to have a healthy and smart baby. However, China is still a country with a high incidence of birth defects, with a high incidence of congenital stupidity and neural tube abnormalities. Genetic factors and environmental factors such as noise pollution, radioactive pollution, chemical pollution, microbial pollution, etc. are the main causes of the birth of children with congenital defects, a healthy couple may be born with congenital defects, and there is no effective treatment after birth. In Europe and the United States and other developed countries have been popularized as a routine monitoring program for pregnant women. Therefore, it is recommended that all pregnant women who are able to do so should participate in prenatal screening to reduce the number of births of children with congenital defects. What kinds of defects are usually screened for in prenatal screening? Currently we screen for the following 3 diseases: 1. Trisomy 21 (also known as congenital stupidity, Down’s syndrome), which accounts for 90% of the entire newborn chromosomal disorders, is the focus of prenatal screening. 2, 18-trisomy (also known as Edward’s syndrome). 3, neural tube abnormalities (such as anencephaly, open spina bifida, etc.). Which pregnant women are not suitable for prenatal screening, but recommended for prenatal diagnosis? The incidence of chromosomal abnormalities increases with the age of the pregnant woman, and the older she is, the more she needs prenatal diagnosis. 2. Pregnant women who have a history of chromosomal abnormalities have a higher risk of giving birth to such children again. 3.Pregnant women who have a history of repeated miscarriages and unexplained stillbirths. 4. Pregnant women with a family history of genetic diseases who have delivered babies with severe congenital defects. 5. Pregnant women with high risk of prenatal screening. 6. Pregnant women with a history of exposure to environmental teratogenic factors.