The XY chromosome is the sex chromosome, which is the pair of chromosomes that determines the sex of the fetus. In humans, there are 23 pairs of chromosomes, and each pair has two chromosomes, that is, there are 46 chromosomes. Changes in the location of chromosomes or localized deletions, duplications, or growths can change the human body to a greater or lesser extent, and in severe cases can cause serious diseases in the human body. The main chromosomes that are now screened in obstetrics clinics are trisomy 21, trisomy 18, and trisomy 13. In early pregnancy, which is around 11-13 weeks of pregnancy, ultrasound and NT screening is performed, which is a preliminary screening for chromosomal developmental abnormalities in the fetus. In the second trimester, there is Down’s syndrome screening and non-invasive DNA testing to detect chromosomal abnormalities in the fetus, mainly Down’s syndrome. The XY chromosome is a sex chromosome that can determine the sex of the fetus.