The occurrence of cardiovascular malformations is mainly due to genetic and environmental factors and their interactions. Intrinsic factors are mainly related to genetics, with single gene and chromosomal abnormalities causing about 15% of all congenital heart diseases. For example, about 40% of children with trisomy 21, or congenital dysmorphism, have a combination of cardiovascular malformations, with atrial septal defects being the most common. Marfan syndrome is associated with the Fibrillin gene; supra-aortic stenosis may be associated with mutations in the Elastin gene. The more important external factors are (1) intrauterine infections, especially viral infections such as rubella, influenza, mumps and coxsackievirus infection in early pregnancy; (2) maternal exposure to a large amount of radiation or drugs (such as anti-cancer drugs, anti-epileptic drugs, etc.); (3) metabolic diseases (such as diabetes, hypercalcemia); (4) alcohol and drug abuse in early pregnancy; (5) chronic diseases causing intrauterine hypoxia in pregnant women. chronic diseases that cause intrauterine hypoxia. Although the etiology of congenital heart disease has not been completely clarified so far, it is important to strengthen the health care of pregnant women, especially to actively prevent rubella, influenza and other viral diseases in the early stage of pregnancy, i.e. the first three months of pregnancy, and to avoid exposure to high-risk factors related to the development of congenital heart disease.