1. Immunological factors (50-60%): The process of embryo implantation is a process of immunological recognition of the baby by the mother, i.e. mother-fetus dialogue. In this dialogue, the fetus and the mother adapt to each other to produce a positive immune response that facilitates embryo survival and pregnancy maintenance. If the number and function of immune cells in the maternal blood or endometrium are abnormal, it may trigger immune rejection of the fetus by the mother, leading to an increased risk of miscarriage or complications in the middle and later stages of pregnancy. 2. Coagulation abnormalities (20-25%): Antiphospholipid antibodies are an important factor causing maternal hypercoagulable tendency. Antiphospholipid antibodies in maternal blood can damage the vascular structure, leading to the formation of thrombus or narrowing of the vascular diameter in the blood vessels supplying the fetus, affecting the maternal supply of nutrients to the baby and interfering with the growth of fetal cells, causing the fetus to stop developing. 3.Chromosomal abnormalities (2-4%): Chromosomal abnormalities in either or both parents, such as balanced translocation and Robertson translocation, can lead to chromosomal abnormalities in the fetus. 4.Other factors (10-30%): endocrine abnormalities, reproductive organ abnormalities, infections, male factors, environmental factors, psychological factors such as insomnia, depression, high work pressure, etc. It can be seen that the causes of recurrent miscarriage are complex, and patients need to be investigated one by one under the guidance of a specialist to identify the causes and then carry out targeted treatment in order to reduce the risk of recurrent miscarriage and make the baby grow healthily in the mother’s womb.