In clinical practice, we call miscarriage within 28 weeks of gestation as spontaneous miscarriage; miscarriage within 12 weeks as early miscarriage; miscarriage between 12-28 weeks as late miscarriage; spontaneous miscarriage for 2 or more times in a row as recurrent miscarriage, also called habitual miscarriage. The causes of spontaneous miscarriage are mainly the following five categories: a. Chromosomal abnormalities: the main cause of recurrent miscarriage, including chromosomal number and structure abnormalities. This is the natural selection and self-protection strategy of the human body. Endocrine abnormalities: mainly caused by insufficient luteal function of ovaries during pregnancy. Third, anatomical abnormalities of the uterus: for example, small uterine development, double uterus, longitudinal uterus, uterine cavity adhesions or combined myoma, etc. Immunological factors: the fetus comes from both parents’ genes and is a semi-isogamous graft, according to the inference, the fetus has half the chance of being rejected, but the majority of pregnancies are successful, which modern medicine believes is closely related to the immune regulation mechanism between mother and fetus. V. Those with unclear causes. Women suffering from habitual miscarriage after the previous miscarriage and before the next pregnancy should go to the hospital with their husbands for a detailed examination to find out the cause and then treat the cause. If the miscarriage is caused by luteal insufficiency, hypothyroidism and other disorders, medication can be given; if the miscarriage is caused by uterine malformation, uterine fibroids, or official adhesions, surgery is feasible. Even if the pregnancy is delivered at term without miscarriage, the incidence of fetal abnormality is higher. There is no special treatment for chromosomal abnormalities, so it is best for these couples to use contraception and avoid pregnancy. If you want to have a baby, you must go to the hospital at 4-5 months of gestation to check the fetal shed cells for chromosomal abnormalities, or use B-ultrasound to check the fetal abnormalities. The fetal abnormality should be terminated immediately if it is found. Avoid giving birth to a deformed fetus which will cause misfortune to the society and family. In case of late miscarriage due to relaxation of the endocervix, endocervical suturing can be performed at the hospital between 12 and 20 weeks of gestation, before the month in which the miscarriage occurs, to tighten the endocervix. After the procedure, bed rest is provided in the hospital until after the month of pregnancy in which the miscarriage previously occurred, and then the cervical suture is removed at full term. For women with habitual miscarriage of unknown etiology, they should rest in bed when their menstruation is slightly overdue and there is a possibility of pregnancy, prohibit sexual intercourse, take vitamin E and folic acid supplements, take oral sedatives and herbal medicines, and eliminate mental tension. The duration of bed rest and medication must exceed the month of pregnancy in which the miscarriage occurred in the past.