The first definition of spontaneous abortion was three or more consecutive spontaneous abortions. In recent years, the definition has been gradually revised to two spontaneous miscarriages, whether they are consecutive or not, and in certain special cases, it is time to start screening for spontaneous miscarriage factors. The reason why we say special cases is that they may have a higher chance of recurrent miscarriage than the average spontaneous miscarriage patient. For a patient with 2 spontaneous abortions, the chance of recurrence of pregnancy is about 30%, which means that without any treatment, there is a 70% chance of a successful recurrence. What are the special types of patients? 1. spontaneous miscarriage with a large month, a heartbeat with a fetal bud detected by ultrasound before the miscarriage, and then an ultrasound after a period of vaginal bleeding that reveals embryonic abortion; 2. a woman older than 35 years; 3. a couple with difficulties in conceiving; 4. a nervous couple; 5. sporadic menstruation, PCOS (polycystic ovary syndrome); 6. a normal karyotype detected in the embryo at the time of spontaneous miscarriage.