With the liberalization of the domestic second-child policy, more pregnant women with mechanical valves will be created, and anticoagulation strategies during pregnancy will become more and more important, so I will briefly explain them to you today. Since the first prosthetic mechanical valve was implanted in humans in 1961, thousands of patients have benefited from it. Lifelong anticoagulation is required after mechanical valve replacement. Warfarin is the most commonly used and the only oral anticoagulant available for mechanical valve replacement patients in China, and the first reported case of a mechanical valve patient who was pregnant to term was in 1966. Warfarin is a bicoumarin derivative, which exerts its anticoagulant effect by inhibiting the interconversion of vitamin K and vitamin K epoxide. However, warfarin has a small molecular weight and can pass through the placenta, causing malformations such as nasal hypoplasia, epiphyseal detachment, optic nerve atrophy, and mental retardation, as well as miscarriage, preterm delivery, and stillbirth. Warfarin can also cause maternal hemorrhage and other complications. It has a pregnancy drug classification of D (clear hazard to the fetus; nevertheless, there is an absolute benefit to pregnant women with the drug). The choice of anticoagulation regimen during pregnancy in patients after mechanical valve replacement has confused many patients, obstetricians and gynecologists, and cardiac surgeons. What is the best way to minimize the risk to the mother and fetus? 1. The effect of different anticoagulation regimens on pregnant women: the risk of valvular thrombosis in pregnant women with oral warfarin anticoagulation throughout pregnancy was 3.9%; the risk of valvular thrombosis in pregnant women with heparin anticoagulation in the first 3 months of pregnancy and oral warfarin anticoagulation in the middle and last trimester was 9.2%; and the risk of valvular thrombosis in pregnant women with heparin anticoagulation throughout pregnancy was 33%. The corresponding maternal deaths due to valve thrombosis were 2%, 4%, and 15% in each group, respectively. All anticoagulation regimens increase the risk of miscarriage, retroplacental hemorrhage, preterm delivery, and stillbirth. However, compared to heparin and low molecular heparin, warfarin causes 0.6C10 % risk of placental abnormality and 1 % risk of central nervous system abnormality in the first trimester due to its ability to cross the placenta, and in addition, oral anticoagulation by the mother is contraindicated for fetal transvaginal delivery and can cause intracranial hemorrhage in the fetus. Given the risk of heparin and low-molecular heparin valve thrombotic events, no heparin or low-molecular heparin is currently approved for use in women with mechanical valve pregnancies. Moreover, the risk of fetal malformation is relatively small (less than 3%) with low doses of oral warfarin (less than 5 mg/day) and rigorous INR testing. Therefore, the 2011 European Society of Cardiology guidelines suggest that oral warfarin anticoagulation is recommended for the entire duration of pregnancy in pregnant women taking less than 5 mg/day of oral warfarin, and in pregnant women taking more than 5 mg/day of oral warfarin, heparin (to detect APTT values) or low molecular heparin (to monitor anti-Xa activity) is recommended for the first 3 months of pregnancy, and oral warfarin anticoagulation is recommended for the middle and last 3 months of pregnancy in view of the significantly increased teratogenic risk of warfarin. oral warfarin anticoagulation. The American College of Chest Physicians, on the other hand, believes that the increased risk of thromboembolism with heparin or low-molecular heparin in the first trimester of pregnancy is due to the fact that the population enrolled in these studies was itself older women, who were more prone to thrombosis and to inappropriate doses of heparin. They therefore recommend the use of low-molecular heparin in the first trimester for low-risk pregnancies and oral anticoagulants throughout pregnancy for high-risk pregnancies. The maternal state of hypercoagulation during pregnancy makes it more prone to mechanical valve thromboembolic events and requires higher anticoagulation. At present, it seems that regardless of the anticoagulation regimen, pregnant women and fetuses are exposed to certain risks. However, in combination with the high sensitivity of warfarin in our population, most patients taking oral warfarin doses less than 5 mg/day have a relatively low incidence of fetal malformations. The Chinese expert consensus on warfarin anticoagulation states that for patients with implanted prosthetic mechanical valves, the best strategy is to give warfarin anticoagulation and closely monitor INR. Our opinion is that, in general, full warfarin anticoagulation is focused on the protective effect on the mother, and replacement with low molecular heparin in the first trimester leads to less protective effect on the pregnant woman, but seems to be more beneficial to the fetus. Therefore, for small doses of warfarin anticoagulation (tentatively 5 mg, the smaller the safer), we advocate full warfarin anticoagulation, while for large doses of warfarin maintenance >5 mg, we also advocate full warfarin anticoagulation from the point of view of maternal protection, unless she has done so in her first pregnancy and the fetus has developed serious problems, in which case, alternative anticoagulation with low-molecular heparin in the first trimester can be tried. . Due to the individual differences in pregnant women, their economic situation, and the underlying conditions of the hospital, anticoagulation protocols during pregnancy in patients after mechanical valve replacement need to be determined by a combination of factors.