Squatting phenomenon refers to a special forced position, mainly due to a child with congenital tetralogy of Fallot, who will have a special position of bending his legs to follow the fraud section when walking, or sitting, and then will return to normal walking, which will occur repeatedly. Tetralogy of Fallot is a joint congenital cardiovascular malformation, including four conditions such as pulmonary artery orifice stenosis, ventricular septal defect, right aortic position (riding on the defective ventricular septum), and right ventricular hypertrophy, so what are the reasons for the appearance of this phenomenon? Here we will learn together. The causes of squatting phenomenon: 1, environmental causes (1) infection, the first trimester of pregnancy with viral or bacterial infections, especially rubella virus, followed by coxsackievirus, the birth of babies with a higher rate of congenital heart attacks. (2) other: such as amniotic membrane lesions, fetal compression, early pregnancy preterm abortion, maternal malnutrition, diabetes, phenylketonuria, hypercalcemia, the application of radiation and cytotoxic drugs in early pregnancy, the mother is too old, etc. have the potential to cause congenital heart disease in the fetus. 2, genetic causes Congenital heart disease has a certain degree of family tendency to attack, may be due to parental germ cells, chromosomal aberrations caused by. The genetic studies suggest that most congenital heart disease is formed by the interaction of multiple genes and environmental causes. 3, other causes Some congenital heart disease in the highlands more, some congenital heart disease has obvious differences between the cab attack, indicating that the altitude of the birthplace and also related to the occurrence of the disease.