Heparin sodium injection can improve the microcirculation of pregnant women and play the role of anticoagulation, which can increase and improve the blood flow of the placenta and prevent miscarriage. Some pregnant women with recurrent miscarriage are due to antiphospholipid syndrome, easy thrombosis, etc., which leads to dysfunction of coagulation, anticoagulation and fibrinolytic system in pregnant women, resulting in decreased circulation in the placenta, causing chorionic villus infarction and fibrinoid necrosis of the meconium blood vessels, which hinders the exchange of substances between the fetus and the mother, thus causing miscarriage, preterm labor, and preeclampsia. However, pregnant women can not apply heparin sodium privately to protect the fetus, must be under the guidance of a doctor, there are indications for the use of heparin sodium can be applied, and in the process of the application of regular monitoring of coagulation function.