Preterm birth refers to delivery between 28 and 36+6 weeks of pregnancy. Due to the lighter weight and lower maturity of the fetus at this stage, the survival rate of newborns is often reduced. The causes of preterm birth include the following aspects: First, the presence of vaginal inflammation can easily lead to premature rupture of membranes, which in turn triggers contractions and can lead to preterm labor. Second, in twin or multiple pregnancies, the increased irritability of the uterine wall can easily cause spontaneous contractions, which in turn lead to preterm labor. Third, an excess of amniotic fluid can increase the pressure inside the amniotic cavity, easily stimulating spontaneous uterine contractions or premature rupture of membranes. Additionally, if the cervical canal is congenitally short, or if there has been previous cervical surgery, this can also easily lead to preterm labor.