The non-invasive test for pregnant women screens for fetal chromosomal disorders, including three major chromosomal disorders, such as trisomy 21, trisomy 18 and trisomy 13, three common fetal congenital dysmorphisms. The test is performed by drawing venous blood from a pregnant woman and sequencing the free DNA fragments in the peripheral plasma of the female mother using DNA sequencing technology, and the sequencing results are used for further analysis of biological information. Currently, the following groups of people are widely used in clinical practice and must be tested: 1) pregnant women aged >35 years old; 2) women with high risk of Down’s syndrome screening or with high values of single indicators, as well as pregnant women who are not suitable for puncture tests, such as those carrying viruses, low placental position, low amniotic fluid or Rh-negative blood; 3) pregnant women with a history of multiple miscarriages, abnormal NT through pregnancy testing or with other Pregnant women with abnormal fetal development who voluntarily undergo the test and prefer to and more accurately rule out trisomy 21, trisomy 18, trisomy 13; 4. Pregnant women with family history of hereditary diseases. Free screening has been implemented in most areas of China, and free screening is available by building a file at the maternal and child health center in one’s area of residence.