晚期自然流产是指由自然因素导致的妊娠时间大于12周不足28周,且胎儿体重不足1 000 g而终止妊娠者。胚胎着床后31%发生自然流产,其中80%为早期流产~([1])。晚期流产最常发生于妊娠18~25周,通常表现为阴道流血,不规则下腹痛,腰酸及下坠感等症状,严重者可导致胚胎死亡 Late spontaneous abortion refers to the natural cause of pregnancy more than 12 weeks less than 28 weeks, and the fetus weighing less than 1 000 g and termination of pregnancy. Spontaneous abortion occurs in 31% of the embryo after implantation, of which 80% is early abortion ~ ([1]). Late abortion most often occurs in 18 to 25 weeks of pregnancy, usually manifested as vaginal bleeding, irregular lower abdominal pain, backache and falling flu and other symptoms, severe cases can lead to embryonic death