Preterm labor includes spontaneous preterm labor and therapeutic preterm labor, the common causes are as follows: 1, previous history of preterm labor, the current pregnancy interval <18 months, or >5 years, the cause of vaginal infection, intrauterine infection, uterine hyperinflation, and even placental factors can cause preterm labor; 2, preterm labor caused by premature rupture of membranes occurred before the gestational week <37 weeks, related to personal habits, such as smoking history, drinking history, excessive labor, can be Full-term water breakage occurs. Previous premature rupture of membranes with body mass index <19.8kg/㎡ can also cause premature rupture of membranes without bleeding; 3. Therapeutic preterm labor is generally caused by medical treatment, which is common in cases of complications of hyperemesis before 37 weeks of pregnancy, requiring surgical termination of pregnancy, as well as premature labor caused by intrauterine distress and low amniotic fluid, requiring early termination of pregnancy.