1. Genetic factors (1) Embryonic/fetal chromosomal abnormalities are the most common cause of fetal abortion. Various types of chromosomal abnormalities can be detected in more than 60% of miscarried or arrested embryos, especially more than 80% of arrested/aborted embryos with abnormal gestational sac morphology have chromosomal abnormalities; even aborted/aborted embryos with normal gestational sac morphology have chromosomal abnormalities in about 25% of them. It was found that the earlier the time of miscarriage/arrested development, the higher the rate of chromosomal abnormalities. (2) Chromosomal translocations or inversions in one of the spouses (parental generation) lead to chromosomal abnormalities in the fetus, which in turn leads to arrest of development. Couples with a history of fetal arrest are seen with balanced chromosomal translocations, rosette translocations, and inversions. Parental chromosomal translocations have serious adverse genetic reproductive effects: if one spouse is a balanced carrier, there is a 1/18 chance that the offspring will be chromosomally normal, 1/18 will be a balanced carrier, and the remaining 16/18 will be unbalanced abnormalities, often resulting in birth defects or death. Genetic counseling for parental chromosome rosettes: If one spouse is a carrier of chromosome rosettes, their offspring have 1/6 normal chromosomes, 1/6 carriers of chromosome rosettes, and the other 4/6 are unbalanced abnormalities, which manifest as developmental defects or death. Parental chromosome inversion carriers: their offspring have 1/4 normal chromosomes, 1/4 chromosome inversion carriers, and 2/4 unbalanced abnormalities. (3) Gene mutation and fetal abortion. Some genes play a role in promoting the occurrence of miscarriage in the process of miscarriage and are called miscarriage susceptibility genes; some genes prevent the occurrence of miscarriage and play a protective role in maintaining pregnancy. In addition, fetal pure gene mutation or compound heterozygous mutation can lead to abnormal fetal development or even death. 2, maternal factors (1) maternal chronic diseases, reproductive tract infections, malnutrition, etc. can lead to the occurrence of miscarriage. Especially TORCH infection, Toxoplasma gondii infection, rubella virus infection, cytomegalovirus infection, herpes simplex virus infection, mycoplasma and chlamydia infection, etc. can lead to abnormal fetal development through vertical infection. (2) Anatomical abnormalities of reproductive organs: such as uterine malformations, uterine adhesions, uterine fibroids, uterine polyps, uterine adenomyosis and cervical insufficiency, etc. (3) Coagulation abnormalities: microthrombosis. (4) Endocrine factors: abnormal luteal function, abnormal placental function, polycystic ovary syndrome, hyperprolactinemia, thyroid disease and diabetes mellitus, etc. (3) Paternal factors The male partner suffers from chronic systemic diseases, infection with pathogenic microorganisms, semen abnormalities, bad habits, exposure to occupational factors, and the production of anti-sperm antibodies, etc. 4, immune factors Immune factors that cause fetal abortion include: ABO/RH maternal and child blood type incompatibility, maternal rejection, blocking antibody deficiency, antiphospholipid antibody syndrome, as well as cytotoxic effects and increased activity of the complement system. 5, mental factors Pregnant women or women of childbearing age have anxiety, depression, low self-esteem, guilt, autism, pessimism, insomnia and other adverse emotions, which lead to low body function and preferably cause immune dysfunction and finally lead to abnormal fetal development.