After pregnancy, there are three significant changes in the body concerning the circulatory system: first, an increase in circulating blood volume, second, an increased burden on the heart, and third, an increased ability of the blood to clot. Therefore, anticoagulation therapy during this period is particularly important for pregnant women who have artificial mechanical valves implanted in their hearts or who have deep vein thrombosis. If anticoagulation therapy is not appropriate, it may lead to fetal miscarriage in mild cases or to the death of both mother and child in severe cases. The effects of anticoagulation therapy on pregnancy and childbirth are mainly in three areas: 1) the pathogenicity of anticoagulants to the fetus; 2) placental hemorrhage due to anticoagulation therapy, including minor and multiple placental hemorrhages during pregnancy or hemorrhage during labor; and 3) the effects of anticoagulants on the fetal coagulation system. The issue of pregnancy and childbirth in patients treated with anticoagulation using warfarin is a relatively 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 (benzoyl 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. Regular heparin has a short half-life, its anticoagulant effect can be neutralized by fisetin, and is inexpensive. Low-molecular heparin has a long half-life and a better anticoagulant effect, but its effect cannot be neutralized by fisetin, and it is expensive. Heparin is characterized by 1) a large molecular weight, and neither normal nor low molecular heparin crosses the placental barrier and therefore has no effect on the fetus; 2) it may cause reversible osteoporosis, alopecia, or heparin-induced thrombocytopenia; 3) there is some disagreement about the effectiveness of heparin in preventing mechanical valve thrombosis, i.e., its effectiveness has not been fully confirmed. The Federal Food and Drug Administration (FDA) has issued a specific warning and a request 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 administered subcutaneously once every 12 hours and the level of anticoagulant factor Xa (anti?Xa in English) should be between 0,7 U/ml and 1,2 U/ml 4 hours after administration. Warfarin is characterized by 1. small molecular weight and can cross the placental barrier; 2. can cause fetal malformations, mainly midline skeletal dysplasia of the jaws and face, such as cleft lip, cleft palate and collapsed nasal bridge It occurs within the first 3 months of pregnancy, i.e., the stage of fetal formation. The probability of malformation is reported to be about 6% and is related to the dose of warfarin. If the dose is below 5 mg per day, the incidence is not high. The Chinese population is mostly below this dose.3. It can lead to intra-fetal hemorrhage, especially after birth. Regardless of the type of anticoagulant, its use during pregnancy has the potential to cause placental hemorrhage. The main cause of miscarriage in anticoagulant-treated pregnant women is thought to be placental hemorrhage. Clinically, there are three options for anticoagulation in pregnant women with artificial mechanical valves. The first is anticoagulation with low-molecular heparin from the sixth to the twelfth week of gestation, followed by a switch to warfarin. The second is full heparin anticoagulation. The third is full warfarin anticoagulation. If only the fetus is at risk or at risk and the mother’s safety is ensured, then the mother can become pregnant again. If the mother is at risk, the fetus must also be at the same risk. Therefore, my personal opinion favors full warfarin anticoagulation therapy with prenatal heparin replacement. The coagulation factor production system in the fetal liver is immature, its blood is low in vitamin K-dependent coagulation factors, and the fetal liver is slow to metabolize warfarin. Also, the crushing and traumatic effects of the birth canal or even forceps on the fetal head during labor may result in small foci of intracranial hemorrhage in the fetus. A therapeutic dose of warfarin in the mother can cause fetal warfarin overdose, resulting in intracranial hemorrhage in the fetus after delivery. Therefore, warfarin anticoagulation therapy should be replaced with heparin starting one to two weeks before delivery so that the effects of warfarin in the mother and fetus are eliminated. Cesarean section should generally be chosen to reduce trauma to the fetal head. The use of forceps is prohibited. Epidural anesthesia should be avoided in favor of general anesthesia to prevent possible intravertebral hematoma caused by lumbar anesthesia, leading to paraplegia. Warfarin anticoagulation should be started immediately after surgery. Warfarin essentially does not pass into breast milk, so it is safe to breastfeed after delivery. Pregnancy and childbirth in women with prosthetic mechanical heart valves is a major concern for the well-being of mother and child. If pregnancy and childbirth are planned, try to use a bioprosthetic valve at the time of valve replacement surgery to avoid this problem at all. Pregnancy does not accelerate the process of bioprosthetic valve destruction. Patients with atrial fibrillation will still require warfarin anticoagulation even if a bioprosthetic valve is used. If a mechanical valve must be used, a hemodynamically effective bileaflet mechanical valve should be selected. Patients who already have a mechanical valve should always consult with a medical professional prior to pregnancy to understand the process, know its risks, and seek the most appropriate option for the patient’s specific situation. If you choose to take warfarin, it is best to limit the dose to less than 5 mg per day and add aspirin if necessary. This matter does carry some risk, both for the mother and the fetus. Please be sure to take it seriously. Warfarin has no effect on male reproductive function.