Tricuspid valve insufficiency (TR) is only a descriptive diagnosis of the functional status of the tricuspid valve and does not convey information about the presence of tricuspid valve malformation or pathology. Therefore, care should be taken to exclude organic lesions of the tricuspid valve in the presence of fetal TR, such as abnormal tricuspid valve development, tricuspid valve agenesis, tricuspid bicuspid malformation, tricuspid valve prolapse, tricuspid valvuloplasty, and Ebstein′s heart malformation. In the absence of organic lesions of the tricuspid valve, functional tricuspid valve insufficiency should be considered. Because the characteristics of fetal cardiac circulation and the functions assumed by the left and right ventricles are different from those of the postnatal period, the fetal right ventricle does not assume the blood pumping function of the pulmonary circulation, but of the body circulation from the arterial duct down; the fetal pulmonary artery has the same middle elastic fiber layer as the body artery structure, and the right ventricle has the same high blood displacement resistance as the left ventricle, so the right ventricle in fetuses, newborns, and small infants tends to The right ventricle is often predominant in fetuses, newborns, and infants. In terms of structural characteristics, the crescentic structure and bellows contraction of the right ventricle differ from the conical structure and fist-pump contraction of the left ventricle, and the triangular opening of the tricuspid valve and the presence of only one group of larger papillary muscles differ from the elliptical opening of the mitral valve and the presence of two groups of larger papillary muscles. These functional and structural characteristics of the tricuspid valve dictate that the fetal heart bears the same peripheral resistance and pressure as the left ventricle with a weaker right ventricle systolic function, an unstable tricuspid opening, and fewer subvalvular papillary muscles. Once there is a small change in fetal circulatory resistance and volume load may cause tricuspid valve closure insufficiency, so some babies in the fetal period may have tricuspid valve closure insufficiency, to be born after the pulmonary resistance is reduced can naturally heal. Health care measures: 1. No special treatment or care is needed during the fetal period; 2. Normal delivery is possible without special delivery measures; 3. Cardiac ultrasound, chest X-ray (orthopantomogram) and electrocardiogram are performed promptly after birth; 4. Treatment: Most mild and moderate tricuspid valve insufficiency does not require treatment, or low-flow oxygen to promote the reduction of pulmonary resistance; severe tricuspid valve insufficiency should be carefully excluded organic lesions, can be treated with low-flow oxygen, sodium nitroprusside, prostaglandin E1 and dobutamine, digoxin, diuretics, etc., to reduce pulmonary resistance and maintain right heart function. Long-term prognosis: Functional tricuspid valve insufficiency can lead to a completely normal life, study and work.