Chromosomal abnormalities in infants may be related to the age of the pregnant woman, autoimmune diseases, biological, physical and chemical factors. 1. Age of the pregnant woman: if she is an advanced maternal age, then the probability of chromosomal abnormality during pregnancy is generally higher than that of a young pregnant woman. 2. Autoimmune disease: If the pregnant woman herself has autoimmune disease, it may also cause chromosomal abnormality in the embryo; 3. Biological factors: If the pregnant woman has low immunity during pregnancy, if she is infected with bacteria or viruses, it is likely to lead to chromosomal abnormalities. 4. Physical factors: if a pregnant woman is exposed to rays or substances with radioactivity for a long time, it will also lead to chromosome abnormalities. 5. Chemical factors: If you are frequently exposed to hair dyes, formaldehyde, etc. during pregnancy, it may also lead to abnormal development of chromosomes during the formation of embryos and the emergence of congenital diseases. Pregnant women should pay attention to avoiding exposure to the above harmful factors during pregnancy, and if they have other diseases, they must undergo regular checkups.