Low-molecular-weight heparin is an anticoagulant drug that can be used to protect the fetus if the woman has fertility requirements or if she is pregnant and has a prethrombotic condition or immune system disease. If the patient has a prethrombotic condition or an immune system disease, the patient is more likely to suffer from a variety of conditions, such as embryo stop development or embryo growth restriction, after pregnancy. The use of LMWH in patients can alleviate the patient's hypercoagulability, enhance the blood supply of embryos, and enhance the nutrition supply during embryo development. Therefore, LMWH can play the role of fetal protection, but it is only an auxiliary treatment, not the main treatment.