In the fourth month of pregnancy, you can choose the appropriate method to induce labor according to the condition of the mother, including Levanox induction and water bladder induction. 1. intra-amniotic Levanox induction: Levanox is injected into the uterine cavity through amniocentesis to induce labor, which can cause necrosis of the meconium tissue in the uterus and produce endogenous prostaglandins, causing uterine contraction and expulsion of the fetus. 2. water bladder induction: If the pregnant mother has liver and kidney function impairment, it is safer to use water bladder induction. If the mother has liver and kidney function impairment, it is relatively safe to use water bladder to induce labor. The water bladder is placed between the uterine wall and the amniotic cavity to increase the pressure in the uterus, stimulate the cervical canal, cause contraction of the uterus, and finally expel the fetus and placenta from the body.