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 precocious heart 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 well understood. 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 somewhat higher than in the rest of the population. After the fourth month of gestation viral infections on the fetal heart will have little effect. 2, drugs and chemical factors: some studies have shown that during the embryonic development of the heart teratogenic sensitive period (i.e. 3-8 weeks of pregnancy) many harmful substances and some drugs that can pass through the placenta can cause congenital heart and large blood vessel malformations, such as certain antibiotics, antipyretic and analgesic drugs. Therefore, pregnant mothers-to-be should not take drugs indiscriminately, if necessary, but also under the guidance of a physician. 3, radiation: ionizing radiation can harm the developing embryo, and can also affect its genetic material, resulting in heart malformations. The most common types of ionizing radiation in hospitals are x-rays and isotopes. Pregnant women who undergo related examinations and treatments must explain the situation to their doctors. Once married and pregnant, women who are engaged in related work should also temporarily leave their original jobs to prevent the possible adverse effects of ionizing radiation. 4, nutritional factors: fetal requirements for nutrition is much higher than the mother, pregnant women lack of certain vitamins can lead to fetal malformations, but must also bear in mind that pregnant women take vitamins is not the more the better. Overdose of vitamin ADE, etc. can also lead to fetal abnormalities. 5, genetic factors: genetic factors do exist, in clinical work, we have encountered a father or mother with precardiac disease, and the children also suffer from related diseases, but the proportion of these patients in the whole of the children with precardiac 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.