The main reasons for the occurrence of lower extremity DVT during pregnancy are as follows: 1) the pregnant woman’s blood is in a hypercoagulable state; 2) the enlarged uterus affects the blood return to the lower extremities; 3) the left iliac vein is anatomically abnormal; 4) patients with a history of previous thrombosis have a 5-10% chance of developing DVT during pregnancy. There are many types of anticoagulant drugs, but the safety of the drugs to the fetus limits the use of most anticoagulants during pregnancy. Heparin: Ordinary heparin has a large molecular mass and generally cannot pass through the placenta, which has no adverse effect on the fetus, and heparin is not secreted from breast milk, which is an FDA-approved Class C drug. Low-molecular heparin does not pass through the placenta and has no adverse effects on the fetus, and the adverse effects on pregnant women are less than those of heparin. Sodium pentosan: It is a class B drug in pregnancy and has been reported in the literature that it does not pass through the placenta, but the safety of sodium pentosan to the mother and fetus needs further verification. Warfarin and other coumarin-based oral anticoagulants can pass through the placenta and can be teratogenic in early pregnancy and cause fetal microcephaly in late pregnancy, which can lead to fetal warfarin syndrome, neurological abnormalities, miscarriage and preterm delivery. Warfarin is protein bound and is rarely secreted from breast milk. Therefore, mothers who use heparin or coumarin after delivery can breastfeed. Aspirin may have a teratogenic effect on early pregnancy, but it has not been confirmed. It is an FDA-approved Class C drug and can be used during pregnancy, but long-term high-dose use has been reported to be teratogenic. High doses of aspirin during pregnancy can cause neonatal jaundice, and when applied 1 week before delivery, attention should be paid to its effect on the coagulation function of mother and child. Low-molecular dextran is the most commonly used safe drug to reduce blood viscosity with proven clinical efficacy in obstetrics. However, it is necessary to pay attention to its adverse effects such as increasing cardiac and renal burdens by volume expansion and causing allergic reactions as an antigen. In recent years, it has been used less frequently due to its allergic reactions. Our experience after the detection of DVT during pregnancy, low molecular heparin sodium was given twice a day for therapeutic use and once a day for prophylaxis; after delivery, patients were advised to avoid breastfeeding and switch to warfarin, taken orally, for treatment.