It is not too late to start taking heparin at 6 weeks of pregnancy, but it is necessary to take heparin only when there are indications and no contraindications under the guidance of a doctor. Heparin is a natural anticoagulant substance. Pregnant women are hypercoagulable when they are pregnant and are prone to forming blood clots, especially lower extremity venous thrombosis and pulmonary embolism. Heparin has an anticoagulant effect, and heparin injections in pregnant women can prevent the formation and recurrence of blood clots. Usually it needs to be injected until after the 3rd month of pregnancy, when the placenta grows out and the growth and development of the fetus is stable. It is not too late to start injecting heparin at 6 weeks of pregnancy. Heparin is suitable for pregnant women suffering from thrombophilia and autoimmune diseases, such as systemic lupus erythematosus, antiphospholipid antibody syndrome, etc., which are prone to thrombosis during pregnancy, and it is recommended that pregnant women follow the doctor’s instructions to inject low molecular heparin. Heparin needs to be injected in regular hospitals, but not all pregnant women need to be injected, if the pregnant woman does not have a history of miscarriage, does not suffer from hyperthrombophilia or autoimmune diseases, there is no need to deliberately inject heparin.