From the embryonic development of the heart to the circulatory changes that occur before and after birth, the pediatric cardiovascular system undergoes an intricate evolution during development, and the slightest error in any part of this complex process can lead to malformations of the cardiovascular system. Why does my baby have precardiac disease? This is a question that many young mothers and fathers are eager to understand, and it is also a question that doctors often encounter in their clinical work. Frankly speaking, the exact cause of precocious heart disease is still not very clear, through a large number of case studies, the main factors are the following: ① Viral infections: it is generally believed that the incidence of precocious heart disease in babies born to mothers with viral infections such as influenza and rubella in the early stages of pregnancy (within 3 months) is higher than in other groups. Viral infections after the 4th month of gestation have little effect on the fetal heart. ②Drugs and chemical factors: Some studies have shown that many harmful substances and some drugs that can pass through the placenta can cause congenital heart and large blood vessel malformations during the teratogenic sensitive period of embryonic development (i.e. 3-8 weeks of pregnancy), such as certain antibiotics, antipyretic and analgesic drugs, etc. Therefore, pregnant mothers-to-be must not take drugs indiscriminately, and if necessary, they must do so under the guidance of a physician. Radiation: Ionizing radiation can harm the developing embryo and can affect its genetic material, thus producing heart malformations. The most common types of ionizing radiation used in hospitals are x-rays and isotopes, and pregnant women must explain this to their doctors when undergoing relevant examinations and treatments. Women who are engaged in related work should also temporarily leave their original jobs once they are married and pregnant to prevent the possible adverse effects of ionizing radiation. Nutritional factors: The fetus’ nutritional requirements are much higher than the mother’s, and a lack of certain vitamins can lead to fetal malformations, but it must be remembered that the more vitamins a pregnant woman takes, the better. Overdose of vitamin ADE, etc. can also lead to fetal abnormalities. Genetic factors: Genetic factors do exist. In our clinical work, we have come across cases where the father or mother has a precocious heart disease and the child also has a related disease, but the percentage of these patients in the total number of children with precocious heart disease is very low. We have also encountered very rare cases with a familial distribution in our center, and studies are still in progress. In addition to the above factors, there are some other clinical phenomena related to the occurrence of cardiac malformations, for example, the incidence of fetal cardiac malformations increases with maternal age; some mothers-to-be have endocrine or metabolic abnormalities in their bodies, and their fetuses are relatively susceptible to precocious heart disease. It is important to note that the occurrence of many precocious heart diseases cannot be explained by a single factor, but may be the result of the interaction of a number of environmental and genetic factors. Although the exact cause cannot be found in most patients, the majority of medical practitioners and researchers are working hard to explore it, and as basic disciplinary research continues to refine to the molecular and genetic levels, these studies are gaining ground in localized areas that are making continuous progress.