After pregnancy, there are three significant changes in the body related to the circulatory system: firstly, an increase in the volume of circulating blood, secondly, an increase in the burden on the heart, and thirdly, an increase in the ability of the blood to coagulate. Therefore, for pregnant women with prosthetic mechanical valves implanted in the heart or with deep vein thrombosis, anticoagulation therapy during this period is particularly important. If anticoagulation therapy is not appropriate, it can lead to miscarriage of the fetus in mild cases and death of both mother and child in severe cases. The effects of anticoagulation therapy on pregnancy and childbirth are mainly reflected in three aspects. 1, the pathogenicity of anticoagulants on the fetus; 2, placental bleeding caused by anticoagulation therapy, including tiny multiple placental bleeding or hemorrhage during pregnancy and bleeding during delivery; 3, the effect of anticoagulants on the fetal coagulation system. The issue of pregnancy and childbirth in patients undergoing anticoagulation therapy with the application of warfarin is a complex one. There are two types of anticoagulants that can be used clinically, namely vitamin K antagonists and heparin. Commonly used vitamin K antagonists include warfarin (benzylketone coumarin) and neoanticoagulation (vinblastine coumarin). Warfarin is a synthetic drug and is the most widely used of the coumarins. There are two types of heparin, regular heparin and low molecular heparin. Ordinary heparin has a short half-life, and its anticoagulant effect can be neutralized by ichthyoglobulin, which is inexpensive. Low molecular heparin has a long half-life and better anticoagulant effect, but its effect cannot be neutralized by fischer’s protein and it is expensive. The characteristics of heparin are: 1, high molecular weight, both ordinary heparin and low molecular heparin do not cross the placental barrier, so they have no effect on the fetus; 2, may lead to recoverable osteoporosis, alopecia, or heparin-induced thrombocytopenia; 3, there is some disagreement about the effectiveness of heparin in preventing thrombosis in mechanical valves, i.e., its efficacy has not yet been fully recognized. The U.S. Federal Food and Drug Administration (FDA) has issued special warnings and asked for caution regarding the use of low-molecular heparin for anticoagulation in patients with mechanical valves. In its guidelines, the American Heart Association recommends that in pregnant women with prosthetic mechanical valves who are treated with heparin instead of warfarin, regular heparin should be administered intravenously or subcutaneously, and the patient’s partially activated prothrombin time (aPTT) should be maintained at twice the control value. If low molecular heparin is used, it should be given subcutaneously once every 12 hours, with anticoagulant factor Xa (anti?Xa in English) levels ranging from 0.7 U/ml to 1.2 U/ml 4 hours after administration. Warfarin is characterized by: 1. Small molecular weight, which can cross the placental barrier; 2. It can lead to fetal malformations, mainly skeletal midline dysplasia of the maxillofacial region, such as cleft lip, cleft palate, and collapsed nasal bridge , occurring within 3 months after the start of pregnancy, the stage of fetal formation. The probability of the malformation appearing is reported to be about 6% and is related to the dose of warfarin. The incidence is not high if it is under 5 milligrams per day. Chinese people are mostly below this dose. 3, can lead to fetal internal bleeding, especially after birth. Regardless of the type of anticoagulant drug, its use during pregnancy has the potential to cause placental bleeding. The main cause of miscarriage in pregnant women on anticoagulation therapy is thought to be placental hemorrhage. Clinically, there are three options for anticoagulation therapy in pregnant women with prosthetic mechanical valves. The first is anticoagulation with low molecular heparin from the sixth to the twelfth week of pregnancy, followed by a switch to warfarin. The second is full heparin anticoagulation. The third is anticoagulation with warfarin throughout. The coagulation factor production system in the fetal liver is immature, and there are few vitamin K-dependent coagulation factors in its blood, and the metabolism of warfarin by the fetal liver is slow. Also, during labor, the squeezing and traumatic effects of the birth canal and even forceps on the fetal head may result in small intracranial foci of hemorrhage. A therapeutic dose of warfarin in the mother can then cause a fetal warfarin overdose, resulting in postpartum fetal intracranial hemorrhage. Therefore, beginning one to two weeks before delivery, anticoagulation with heparin should be substituted for warfarin so that the effects of warfarin are eliminated in both the mother and the fetus. Cesarean section should generally be chosen to minimize trauma to the fetal head. The use of forceps is prohibited. Epidural anesthesia should be avoided in favor of general anesthesia to prevent intralesional hematoma that may result from lumbar anesthesia and lead to paraplegia. Warfarin anticoagulation should be started immediately after surgery. Warfarin essentially does not pass into breast milk, so breastfeeding is safe after delivery. Pregnancy and childbirth in women with prosthetic mechanical heart valves is a major concern for the well-being of the mother and child. If pregnancy and childbirth are planned, try to avoid this problem at all by using a bioprosthetic valve at the time of valve replacement surgery. Pregnancy does not accelerate the process of destruction of the bioprosthetic valve. Patients with atrial fibrillation still require warfarin anticoagulation even with a biologic valve. If a mechanical valve must be used, a hemodynamically effective bileaflet mechanical valve should be chosen. Patients who already have a mechanical valve should always consult with a medical professional before becoming pregnant to understand the process, be aware of the risks, and seek the option that is best suited to the patient’s specific situation. If you choose to take warfarin, it is best to limit the dose to less than 5 milligrams per day and add aspirin if necessary. This matter does carry some risk, both to the mother and the fetus. Please do take it seriously.