RESUMEN
The 16 afterbirths samples obtained from pregnancies complicated by idiopathic fetal hypotrophy was examined. The criteria of hypotrophy were established: the duration of gestation above 36 weeks, the birth-weight was less than 2500 g. The control group included 8 afterbirth samples from physiological full-term pregnancies. It was performed macroscopic examination, light microscopy and transmission electron microscopy. Macroscopically, no changes were found in the study group apart from the small differences of the weight. Light microscopy showed the retardation of placenta maturation from fetus hypotrophy group, congestion of the villi and presence of the numerous calcifications. Transmission electron microscopy showed the changes of placental barrier elements: adaptation processes and chronic progressive damage of the cells (exfoliation of the endothelial cells from the basal membrane).