Fetal abortion is a condition in which the development of the embryo stops in early pregnancy for some reason, and the ultrasound examination shows an irregular gestational bursa or fetal morphology with no fetal heartbeat, or a withered gestational bursa. This is a clinical category of miscarriage or stillbirth. There are many reasons for fetal abortion: 1. Endocrine disorders: embryo implantation and continued development depend on the coordination of the complex endocrine system with each other, any one of the links is out of order, can lead to miscarriage. The early development of the embryo requires three important hormone levels, one is estrogen, one is progesterone, and one is human chorionic gonadotropin. As the mother, her own endogenous hormones are insufficient to meet the needs of the embryo, which may result in embryonic abortion and miscarriage. Luteal insufficiency can cause delayed endometrial development and short luteal phase, which can affect the implantation of fertilized eggs or early pregnancy miscarriage. Luteal insufficiency is often accompanied by other glandular function abnormalities, such as hyper- or hypothyroidism, diabetes, androgenism and hyperprolactinemia, etc. These factors are not conducive to embryonic development and are closely related to miscarriage. 2, immune factors: the embryo or fetus in the womb of pregnancy is actually a homozygous transfer, because the fetus is a combination of the genetic material of the parents and the mother can not be identical. The immune maladjustment between mother and fetus causes the mother to reject the fetus. Common autoimmune diseases are systemic lupus erythematosus, scleroderma, mixed connective tissue disease, dermatomyositis, etc. The second is the problem of reproductive immunity, if we carry certain antibodies ourselves, it may affect the development of the embryo. In fact, the detection of antibodies is not quite the same in every hospital, and doctors’ opinions are also not quite the same. From the perspective of our research, we believe that there are four factors that affect the development of the embryo. The fourth is called anti-chorionic gonadotropin antibody, which is an important hormone that is actually secreted seven days after the union of sperm and egg, but if you have this antibody, it will resist the secretion of the hormone and may cause the embryo to stop. 3. Uterus abnormalities: The internal environment of the uterus and the overall environment of the uterus may have an impact on the embryo. The internal environment is the endometrium, if it is too thin or too thick, it will affect the implantation. Miscarriages due to uterine defects account for about 10%-15%, and the common ones are (1) congenital abnormalities of Mullerian ducts including unicornuate, bicornuate and bicornuate uterus resulting in narrow uterine cavity and restricted blood supply. Abnormal development of the uterine arteries can lead to asynchronous müllerianization and abnormal implantation. (2) Uterine adhesions, mainly caused by uterine cavity adhesions and fibrosis after trauma, infection or residual placental tissue. This prevents normal molting and placental implantation. (3) Pregnancy failure can also be caused by reduced blood supply due to fibroids and endometriosis resulting in ischemia and venous dilatation, asynchronous molting, abnormal implantation, and hormonal changes caused by fibroids. (4) Congenital or injurious endocervical relaxation and abnormal cervical development due to intrauterine treatment with ethylene estradiol often lead to miscarriage in midterm pregnancies. (4) Chromosomal problems: Chromosomal abnormalities can also lead to embryonic failure and early miscarriage. Chromosomal abnormalities include quantitative and structural abnormalities, quantitative abnormalities can be divided into aneuploidy and polyploidy, the most common abnormal karyotype is triploidy, and trisomy 16 accounts for 1/3, often lethal. 25-67% of trisomy 21, 4-150% of trisomy 13, and 6-33% of trisomy 18 are bound to miscarriage. Others are haploid (4SX) and tetraploid due to abnormal oogenesis resulting in embryonic failure. Structural abnormalities include deletions, balanced translocations, inversions, overlaps and other closures. Balanced translocations are the most common chromosomal abnormalities. Current research on chromosomal problems suggests that chromosomes pair, interchange and separate to form gametes, and gametes combine to form conjoined gametes. If there is an abnormality in one of the congeners, it results in failure to develop normally and can lead to miscarriage, stillbirth, stillbirth, and malformed children; therefore, prenatal diagnosis is required to prevent the birth of chromosomally affected children. There is no effective treatment for miscarriage and fetal abortion caused by carrying chromosomal abnormalities in Western medicine, and only prenatal genetic counseling and diagnosis can be performed. For chromosomal abnormalities, theoretically there is a chance of delivering normal karyotype and carrier babies, and prenatal diagnosis is done for these couples to ensure the birth of normal babies. Of course, current research has also shown that both couples have normal chromosomes, but chromosomal abnormalities occur during gamete formation and embryo development. For example, if a woman is older than 35 years old and her eggs are aging, she is prone to chromosomal non-separation, resulting in chromosomal abnormalities; semen abnormalities, such as large-headed malformed sperm most of which are diploid, form polyploid embryos after fertilization leading to miscarriage. The influence of adverse environment such as toxic chemicals, radiation, high temperature, etc. can also cause chromosomal abnormalities in embryos. Therefore, the key to preventing chromosomal abnormalities that lead to fetal abortion is to regulate the bodies of both spouses so that the functions of the internal organs are normally coordinated, the yin and yang are balanced, and the best pregnancy is selected and kept away from adverse environments. 5, reproductive tract infection: in addition to the above factors, infection caused by early pregnancy miscarriage is increasingly being paid attention to by scholars at home and abroad. Severe TDRCH infection in early pregnancy can cause embryonic death or miscarriage, while milder infections can also cause embryonic malformations. Studies have shown that cytomegalovirus can cause premature miscarriage and intrauterine fetal death. After maternal infection, the pathogens can travel to the placenta through the bloodstream, causing damage to the chorionic villus and capillary endothelium, and destroying the placental barrier, resulting in miscarriage, embryonic arrest and fetal malformation. In recent years, many studies have shown that mycoplasma infection is related to embryonic arrest, and the positive rate of cervical secretion mycoplasma infection in women with embryonic arrest is significantly higher than that in normal women, and there is a highly significant difference. 6, environmental factors: changes in the physiological state of pregnancy, so that the mother’s absorption, distribution and excretion of therapeutic drugs and various environmentally harmful substances have changed significantly, in the early stages of development, the embryo is extremely sensitive to the impact of therapeutic drugs and environmental factors, at this time, various harmful factors can lead to damage to the embryo, or even loss. Many drugs and environmental factors are important factors in causing early embryonic death or fetal malformations. Environmental hormones can act directly on the central neuroendocrine regulatory system, causing disruptions in reproductive hormone secretion, decreased fertility and abnormal embryonic development. There are various environmental factors that cause miscarriage, including physical factors such as X-rays, microwaves, noise, ultrasound, high temperature, and heavy metals such as aluminum, lead, mercury, and zinc that affect the fertilized egg’s implantation or directly damage the embryo and cause miscarriage. Various chemical drugs such as dichlorohydrin, carbon disulfide, anesthetic gases, oral antidiabetic drugs, etc. can interfere with and impair reproductive function, causing embryo miscarriage, stillbirth, malformation, developmental delay and dysfunction. The early embryonic development can be affected by bad habits such as smoking, alcohol, coffee, drugs, and certain medications.