Four months of pregnancy can be aborted, commonly used method of termination of pregnancy is the use of amniocentesis, the injection of drugs into the amniotic cavity to stimulate the uterus to cause contractions, and finally discharge the products of pregnancy, if there is a history of cesarean section or other complications may need to be cesarean section of the uterus to remove the fetus, the need for the doctor to make a comprehensive judgment. The first thing to do is to do an ultrasound to find out the size of the fetus, the position of the placenta, the amount of amniotic fluid, and to do a gynecological examination, in addition to the routine test of the leukorrhea and also to find out whether the cervix is relatively hard. Clinically, after the injection of drugs, uterine contractions and lower abdominal pain usually occur after 24 hours. The duration of uterine contractions varies depending on the individual. If there is a history of previous labor, the duration of miscarriage will be shorter, and if it is the first pregnancy, the duration of pain will be longer.