The methods to check fetal chromosomes are usually through non-invasive DNA testing or chorionic villus aspiration, amniocentesis, cord blood aspiration, etc., all of which can detect whether there are chromosomal abnormalities in fetal babies, as follows: 1, non-invasive DNA testing: 5ml of venous blood is taken from the pregnant woman, from which the free DNA of the fetus is extracted, and through the method of biological information analysis, the possibility of the fetus suffering from chromosome 21, 18 and 13 is determined. The best time to do fetal chromosome testing is between 18 and 22 weeks, especially between 16 and 20 weeks, when the amniotic fluid contains the most live cells shed from the fetal skin. The amniotic fluid is extracted from the amniotic cavity and about 20 ml of amniotic fluid is used for cell culture, colchicine is added, film is produced, bands are visualized, and finally karyotype analysis is performed after reading the film, and the conventional G bands are between 320 and 400 bands to determine whether the fetal chromosomes are abnormal. All of the above methods can check fetal chromosomes.