Polyhydramnios is relatively common during pregnancy and can have a certain impact on the fetus. There are many reasons that can cause polyhydramnios, but regardless of the cause, polyhydramnios tends to lead to preterm birth. When there is an excessive amount of amniotic fluid, it puts significant pressure on the amniotic sac, which can easily lead to premature rupture of membranes. Premature rupture of membranes itself can stimulate the cervix, release inflammatory mediators, thereby causing contractions and symptoms of preterm labor. After the membranes rupture prematurely, infection within the uterine cavity is likely to occur, generally meaning that the possibility of keeping the pregnancy going for a long duration is unlikely. Therefore, polyhydramnios is associated with a higher risk of preterm labor. In clinical practice, if excessive amniotic fluid is detected during prenatal check-ups, it is advised to control the diet, engage in appropriate physical activities, or use other methods to keep the amniotic fluid level within the normal range.