The main steps for induction of labor at 4 months, including hydrosalping and medication induction, are preoperative disinfection, induction of contractions, and expulsion of the fetus. The pregnant woman needs to improve the relevant examination before the operation to make sure there is no contraindication to the operation. A. Water bladder induction of labor 1. The pregnant woman adopts a bladder truncated position, lies on her back on the examination bed, that is, her buttocks are close to the edge of the bed and placed on the leg brace to expose the perineum to the maximum, and the doctor routinely disinfects the vulva and cervix; 2. After sending all the water bladders into the cervical canal, inject saline from the internal catheter and tie the catheter; 3. Wait for the pregnant woman to have contractions and expel the fetus. 1. The pregnant woman is placed in a flat position, and the doctor carries out routine disinfection; 2. After entering the amniotic cavity with a lumbar puncture needle, the drug is injected into the amniotic cavity, the needle is withdrawn and pressure is applied to stop the bleeding, and then fixed with adhesive tape; 3. Wait for the pregnant woman to have contractions and expel the fetus. Observe the pregnant woman’s signs closely during the operation, including respiration, heart rate, vaginal bleeding, etc.