There are various causes of congenital heart disease in children, let’s understand some of these causes: 1. Factors of fetal development environment: Viral infection in utero is the most important cause of congenital heart disease, among which rubella virus infection is the most prominent, followed by coxsackie virus infection. If a mother suffers from rubella in the first trimester of pregnancy, she will have a higher prevalence of congenital heart disease in her baby; among them, arteriovenous ductus arteriosus and pulmonary valve stenosis are more common. This is due to the fact that the development of the large blood vessels of the fetal heart takes place during the second to eighth week of gestation, when viral infections in the uterus are sufficient to affect the development of the fetal heart. Other causes such as lesions of the amniotic membrane, fetal compression, pre-eclampsia in early pregnancy, maternal malnutrition, diabetes mellitus, phenylketonuria, hypercalcemia, and the use of radiation and cytotoxic drugs in early pregnancy are all causes of congenital heart disease in the fetus. Certain drugs taken by the mother during pregnancy can also lead to fetal heart malformations. 2.Premature birth: Premature birth is an important cause of congenital heart disease. The former is related to the fact that the ventricular septum does not have enough time to complete its development before birth, while the latter is related to the fact that the vasoconstriction response of premature babies is not strong enough after birth. Newborns weighing less than 2500g at birth are especially prone to congenital heart disease. 3, plateau environment: plateau oxygen partial pressure is low is one of the causes of congenital heart disease; plateau area congenital heart disease – arteriovenous insufficiency and congenital heart disease atrial defect more. The prevalence of this disease in Qinghai plateau in China is much higher than that in plain areas. 4, genetic factors: genetic factors are also one of the causes of congenital heart disease. In a family, siblings or parents and children suffer from congenital heart disease at the same time, as well as many cases of chromosomal abnormalities of genetic diseases with cardiovascular malformations, indicating the existence of genetic factors for this disease. Genetic studies have concluded that most congenital heart diseases are the result of the interaction of multiple genes and environmental factors.