Spontaneous abortion is a common occurrence, accounting for 10-15% of all pregnancies. Spontaneous abortion is defined as the termination of a pregnancy at less than 28 weeks of gestation and a fetus weighing less than 1000g. Spontaneous abortion usually occurs within the third month of pregnancy, which is called early spontaneous abortion, and after the third month, which is called late spontaneous abortion. There are many reasons for spontaneous abortion, the main reasons are as follows: firstly, abnormal embryo development, 50%-60% of the embryos with chromosomal abnormalities develop to a certain extent and terminate, and early spontaneous abortion occurs. A small number of embryos with chromosomal abnormalities show malformations or functional defects even if they can develop to full term. Therefore, from a eugenic point of view, this is a natural screening process that follows the law of nature. Secondly, maternal factors. Pregnant women suffer from systemic diseases such as influenza, pneumonia and other acute infectious diseases, and bacterial toxins or viruses enter the fetus through the placenta, causing fetal death. Pregnant women with chronic diseases such as severe anemia, chronic nephritis and hypertension can cause abortion due to placental infarction. High fever can cause miscarriage due to contraction of the uterus. Abnormalities of reproductive organs such as uterine malformation and uterine tumor can affect the embryo’s bed and development and lead to miscarriage. Maternal endocrine dysfunction, such as luteal insufficiency and reduced thyroid function, can cause miscarriage. Bad habits such as excessive smoking, alcohol, coffee, and drug use can also cause miscarriage. Trauma and major mental stimulation can also cause miscarriage due to uterine contraction. There is a complex and special immune relationship between the mother and the fetus so that the mother does not reject the fetus, but if both mothers and children are immune maladjusted, miscarriage will occur. Excessive exposure to environmental factors such as arsenic, lead, formaldehyde, benzene, chloroprene, ethylene oxide and other chemicals can also lead to miscarriage. Spontaneous abortion can be classified into the following four types according to the different stages of development A small amount of vaginal bleeding before 28 weeks of gestation with paroxysmal lower abdominal pain or low back pain, unopened cervical opening, unbroken fetal membranes, unexpelled pregnancy products, and hope for continuation of pregnancy is called pre-eclampsia abortion. After rest and treatment, if the bleeding stops and the lower abdominal pain disappears, the pregnancy can continue. If the vaginal bleeding increases, the lower abdominal pain worsens or there is vaginal fluid flow (rupture of the fetal membranes), it may develop into a refractory abortion. If the condition progresses further and some of the pregnancy products are expelled and some remain in the uterine cavity, an incomplete abortion occurs. As some of the pregnancy products remain in the uterine cavity, it affects the uterine contraction, the uterine bleeding is high, and even hemorrhagic shock may occur. In this case, it is necessary to be admitted to the hospital for examination and urgent clearing of the residual products in the uterine cavity. If all the pregnancy products are expelled, vaginal bleeding gradually stops and abdominal pain gradually disappears, a complete abortion occurs. In addition, there are special types of miscarriage. If the embryo or fetus is dead and remains in the uterine cavity but has not been expelled spontaneously, it is an indolent miscarriage. If spontaneous miscarriage occurs for 3 or more times in a row, it is recurrent miscarriage. After the diagnosis is clear, appropriate treatment should be applied according to the type of spontaneous miscarriage. For pre-eclampsia miscarriage, bed rest, sexual intercourse is prohibited, psychological comfort is provided to stabilize the pregnant woman, and if necessary, sedatives that are less harmful to the fetus can be used. For those who have insufficient luteal function, progesterone can be used for treatment. For hypothyroidism, treatment with small doses of thyroxine is used. After 2 weeks of treatment, vaginal bleeding stops and ultrasound indicates a viable fetus, continue fetal preservation therapy. If the vaginal bleeding does not improve, the amount increases, or the ultrasound indicates embryonic dysplasia, miscarriage is inevitable and the pregnancy should be terminated. In reality, many people are eager to have a baby and ask doctors to do their best to keep the fetus alive, and even take some single prescriptions or test prescriptions without any scientific basis, but the result is not what they want, sometimes even delaying the condition and endangering their lives. From a medical point of view, half of all spontaneous miscarriages are caused by defects in the development of the fertilized egg, and this situation often does not help no matter how to preserve the fetus. Even if the fetus can be maintained until full term, serious malformations and congenital defects are often born, which will not only bring endless troubles to the family, but also create a huge burden to the society. Therefore, you should find out the cause as much as possible before preserving the fetus, and not to blindly preserve the fetus.