Fetal abortion refers to the death of an embryo at one stage of development and the cessation of further development. There are many causes of fetal abortion, mainly including: 1. Chromosomal abnormalities: Chromosomal abnormalities can affect the development of the embryo and lead to miscarriage. Although a few fetuses with chromosomal abnormalities are able to deliver at full term, they often have intellectual disabilities. The study found that the incidence of large Y chromosome karyotype is significantly higher in patients with male azoospermia, sperm abnormalities and spousal early pregnancy embryonic abortion or a history of consecutive miscarriages. 2, environmental factors: the development of industry and urban construction is constantly changing the environment of human life, and the environment has become a factor affecting human reproduction and development can not be ignored, if pregnant women are exposed to certain harmful chemicals or certain physical factors (such as noise, radiation, etc.) too much, including bad habits (such as alcohol, drugs, smoking, etc.) may cause abortion, some studies have shown that early pregnancy Some studies have shown that the occurrence of miscarriage in early pregnancy has seasonal changes, and the possibility of miscarriage in the heating period with high concentration of sulfur dioxide is high, and exposure to relatively high concentration of sulfur dioxide in the perinatal period may increase the risk of miscarriage in early pregnancy. 3, maternal factors: maternal blood, circulatory and urinary system diseases may also affect embryonic development, such as high fever, severe anemia, acute or chronic nephritis, heart failure. In addition, the lack of space in the uterine cavity due to occupational lesions of the uterus, such as uterine adhesions, submucosal fibroids and uterine adenomyoma, can also affect embryonic development. In addition, the occurrence of indolent abortion is also related to the age of the pregnant woman and the number of abortions. In addition, we should pay attention to the problem of embryonic development caused by the influence of men’s life and work. 4. Endocrine factors 1) Insufficient secretion of progesterone can cause poor reaction of the meconium of pregnancy, which can affect the implantation and development of pregnant eggs and lead to miscarriage; 2) After ovulation, insufficient secretion of estrogen may prevent progesterone from fully acting on the endometrium and aggravate the endometrial dysplasia, resulting in embryo implantation and developmental obstruction and sterilization; 3) High androgens can lead to miscarriage due to changes in the immune environment during early pregnancy, and can also directly 4) In the early stage of pregnancy, human chorionic gonadotropin (HCG) can transform the menstrual corpus luteum into gestational corpus luteum and secrete progesterone to protect the embryo from rejection and inhibit maternal rejection of the fetus and placenta; 5) When prolactin (PRL) decreases to a certain level, the corpus luteum stops developing and inhibits the production of progesterone, while excessive PRL can lead to luteal function. Inadequate, so the chance of miscarriage in patients with hyperprolactinism may be higher than normal women. 5, immune factors: reproductive immune antibodies including anti-cardiolipin antibodies (ACA), anti-sperm antibodies (ASAb), anti-endometrial antibodies (EMAb), anti-ovarian antibodies (AOA) and other abnormalities can lead to fetal abortion. 6, blood type disorder: including ABO and RH blood type disorder. In China, the ABO blood type disorder is mainly caused by the mother being type O and the fetus being type A or B. When the ABO blood type disorder occurs, the mother produces IgG antibodies to the A or B antigen, and the lgG antibodies can penetrate into the placenta to produce antigenic antibody reactions leading to miscarriage, and RH blood type disorder can also lead to miscarriage. 7, infection factors: Mycoplasma solium (UU) has a direct toxic effect on the endometrium, which can damage the growth of the fetus and lead to abortion, and Chlamydia (CT) destroys the autoimmune tolerance mechanism of the mother and promotes the loss of embryonic tissue. In summary, there are many causes of fetal abortion, and the specific causes of fetal abortion are different for each pregnant woman. Patients who have experienced fetal abortion should go to the hospital for a comprehensive examination and treatment according to the examination results to avoid recurrence of fetal abortion.