The delivery of fetus and appendages before 28 weeks of gestation is miscarriage, which is divided into early miscarriage and late miscarriage. Early miscarriage is miscarriage before 12 weeks of gestation, and late miscarriage is miscarriage after 12 weeks and less than 28 weeks. Miscarriage is further divided into spontaneous miscarriage and therapeutic miscarriage. According to the different stages of the development of spontaneous miscarriage, it is divided into the following clinical types. 1. Pre-eclampsia miscarriage: It refers to a small amount of vaginal bleeding, often dark red or bloody leucorrhea, followed by paroxysmal lower abdominal pain or low back pain without pregnancy discharge before 28 weeks of pregnancy. If the symptoms disappear after rest and treatment, the pregnancy can continue; if the vaginal bleeding increases or the lower abdominal pain worsens, it can develop into inevitable abortion. 2. Refractory miscarriage: It means that miscarriage is unavoidable. On the basis of pre-miscarriage, the amount of vaginal bleeding increases, the paroxysmal lower abdominal pain intensifies, or the emergence of vaginal fluid (rupture of fetal membranes) and dilatation of the uterus. Incomplete miscarriage: Inevitably, the miscarriage continues to develop and some of the pregnancy is expelled from the uterine cavity, but some of it remains in the uterine cavity or is embedded in the cervical opening, or the placenta stays in the uterine cavity or is embedded in the cervical opening after the fetus is expelled, affecting the contraction of the uterus, leading to bleeding and even shock. 4.Complete miscarriage: It means that the pregnancy has been completely expelled, vaginal bleeding gradually stops and abdominal pain gradually disappears. In addition, there are three special cases of miscarriage: (1) abnormal miscarriage: also known as premature miscarriage, refers to the embryo or fetus has died and is retained in the uterine cavity and not discharged naturally in time. This is because the early pregnancy reaction disappears and there are symptoms of pre-miscarriage or no symptoms at all. If the pregnancy reaches the middle stage, the fetal movement disappears. (2) Recurrent miscarriage: refers to spontaneous miscarriage with the same sexual partner for 3 or more times in a row. (3) Miscarriage combined with infection: During miscarriage, if the vaginal bleeding is long, there is tissue residue in the uterine cavity or illegal abortion, it may cause uterine infection, and the serious infection may extend to the pelvic abdominal cavity or even the whole body, complicated by pelvic inflammatory disease, peritonitis, sepsis and infectious toxic shock. Therefore, miscarriage is manifested with different symptoms according to different types of miscarriage.