Objective To explore the relationship between PROM and dystocia and prenatal complications.Methods 983 cases of lying-in women without pregnant complications and other diseases were analyzed,including 161 cases of PROM,822 cases of not-PROM as control. Results The rates of cesarean section,preterm birth,asphyxia of newborns in PROM were significantly higher than those of control.There was no difference between the frequency of postpartum infections of PROM and that of control.The duration between the rupture of membranes and the delivery,preterm birth was related with the rates of asphyxiat of newborns. Conclusion The PROM is the cause of dystocia and viceversa.Patients of PROM with different week of pregnancy should be treated with different methods to decrease the prenatal complications.