Termination of pregnancy at less than 28 weeks of gestation and a fetus weighing less than 1000g is called miscarriage. Miscarriage caused by natural factors is called spontaneous miscarriage. Spontaneous miscarriage occurs in 31% of normal pregnant women after embryo implantation, so mothers with only one history of spontaneous miscarriage do not need to be nervous and are advised to prepare for another pregnancy after a good preconception checkup. What is recurrent miscarriage? Traditionally, it is defined as 3 or more consecutive spontaneous abortions with the same sexual partner. Although recurrent miscarriage is defined as 3 or more consecutive miscarriages, most experts consider that the risk of 2 consecutive miscarriages is similar to that of 3, i.e. to be taken seriously and evaluated. What causes recurrent miscarriage? The cause of recurrent miscarriage is also very complex, and it may be caused by a single factor or multiple factors. 1. Miscarriages caused by genetic factors cannot be treated, and the abnormal development and cessation of development of these fetuses is a natural elimination process; 2. Miscarriages caused by endocrine abnormalities can be targeted for treatment. Common endocrine abnormalities include luteal insufficiency, polycystic ovary syndrome, hyperprolactinemia, diabetes mellitus and thyroid function abnormalities, if women with these diseases have been found, pregnancy should be considered after the condition is stabilized; 3. common causes. Recurrent miscarriage has some important autoimmune antibodies, the most important of which are antiphospholipid antibodies. The fetus is a homozygous graft and is in the protective mechanism of the mother, in short it is a failure to avoid rejection, a contradiction formed by the fetal system wanting to survive and the maternal system wanting to destroy.