Some recurrent miscarriages and fetal growth restriction are due to the pre-thrombotic state of the pregnant woman’s organism, dysfunction of the coagulation, anticoagulation and fibrinolytic systems, continuous hypercoagulation of the blood in the body, which selectively affects the uteroplacental circulation and leads to placental microthrombosis and microcirculatory disorders, causing a decrease in placental perfusion, resulting in ischemic damage to the placental tissue, which can lead to villi infarction and fibrinoid necrosis of the metaplastic vessels This can lead to fibrinous necrosis of the chorionic villi and metaplastic vessels, impede the exchange of substances between the fetus and the mother, thus promoting miscarriage, preterm delivery, fetal growth restriction, and preeclampsia. The main purpose of heparin is to anticoagulate, improve microcirculation in pregnant women, increase and improve placental blood flow, and thus play a role in fetal preservation. When using heparin to preserve the fetus must be under the guidance of a professional doctor, improper use can lead to bleeding disorders in the body of the pregnant woman, must go to the hospital for consultation and treatment under the guidance of a professional doctor, do not use drugs blindly.