Objective: To investigate the possible effects of the morphological changes in the placenta on fetal prognosis and on umbilical artery and uterine artery Doppler indices in late, low-risk pregnancies. Study design: Placental changes were evaluated ultrasonographically and pathologically in 224 pregnant women after the 25th gestational week. The placental morphology were graded ultrasonographically into five subgroups according to increasing severity of the changes. Postnatally, the neonate was examined, Apgar scores, and adverse events if any, were noted. Placentas with infarction, decidual necrosis, ischemic villitis, chorioangioma, placenta previa or placental abruption and high risk pregnancies were excluded. Results: There were 21, 38, 52, 56 and 57 cases in grades I, II, III, IV, and V respectively. Apgar scores of the babies in all placental grades were similar (P>0.05). In all cases, Doppler indices of both uterine and umbilical artery were within normal limits. No significant association between placental morphological characteristics and Doppler indices of either uterine or umbilical arteries could be demonstrated. There was no correlation between Apgar scores and morphological characteristics of the placenta or Doppler indices. Conclusions: Morphological changes of placental aging are common and seem to have no effect on fetus and on Doppler flow of the umbilical and uterine arteries, provided these are not high-risk pregnancies and placental changes are not infarction, villitis or severe structural or localization anomaly. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.