Abstract: Objective To explore the association between placental premature aging observed ultrasonographically and the pregnancy outcome.Method The perinatal outcome of 30 pregnant women with grade III placenta observed ultrasonographically before 37 weeks of gestation were analyzed retrospectively, with 154 pregnant women with grade Ⅲ placenta at full term (>37 weeks) selected at random to serve as the control.Result The gestational age at delivery (37.38±2.10 weeks) and newborn birth weight (2 802.00±502.99 g) in cases of placental premature aging were significantly lower than those in the control group (39.48±2.44 weeks and 3 324.35±411.34 g, P<0.001), and the incidence of oligohydramnios (26.67%) and rate of cesarean delivery (96.67%) were significantly higher than those in the control group (6.49% and 48.36%, P<0.05).Conclusion The ultrasonographic signs grade Ⅲ placenta maturation before 37 weeks of gestation is associated with oligohydramnios and low birth weight and might help predict placental dysfunction, which needs close monitoring for the benefits of the mother and fetus.