Three and a half months abortion belongs to the mid-pregnancy induction of labor, before induction of labor need to complete the relevant examination: blood routine, blood type, coagulation function, liver and kidney function, vaginal secretion examination, ultrasound, electrocardiogram and so on. Methods of inducing labor include: 1, transabdominal wall amniocentesis to induce labor: ultrasound-mediated amniocentesis should be carried out in the amniotic cavity, amniotic fluid is withdrawn and injected into the levonorgestrel 100mg, when inducing labor, it should be avoided as much as possible to avoid the placenta, and attention is paid to the pregnant woman’s respiratory difficulties, cyanosis, etc. during hospitalization. 2, water bladder induced labor: when inducing labor with a water bladder, the bladder should not be in contact with the vaginal wall as much as possible, and the time of placing it should not be more than 24 hours, the volume of injected water is 300-500ml. The amount of water injected should be 300-500 ml, not more than 600 ml at most, and the contractions should be closely observed and the water bladder should be removed in time.3. Mifepristone with misoprostol for induction of labor: oral medication should be given to flow out the embryonic tissues.4. Cesarean section for fetus extraction: due to the large amount of trauma and complications, it is only limited to the ones who can not tolerate various methods of induced abortion and ask for sterilizing, or those who must end the labor quickly because of the serious complications during the process of induced abortion.