The causes of fetal heart malformation are related to genetic, pathogenic microbial, chemical and physical factors. Maternal factors: 1. maternal diabetes, connective tissue disease (such as systemic lupus erythematosus) 2. viral infection (especially rubella virus) in early pregnancy, history of medication 3. exposure to radiation and chemical agents in early pregnancy 4. advanced maternal age (>35 years old), abnormal pregnancy, family history of precocious heart disease, history of childbirth with precocious heart disease, etc. 2. fetal factors: 1. fetal malformation of other organs: such as 2, chromosomal abnormalities 3, fetal heart rate abnormalities 4, fetal edema 5, amniotic fluid abnormalities 6, fetal intrauterine growth retardation.