The purpose of this research was to study the relationship between placental characteristics and the degree of failure of growth between 37 and 41 weeks of pregnancy. The cases of severe small-for-dates (percentiles of 1 to 5) and moderate small-for-dates (percentiles of 6 to 10) were compared with a control series (percentiles of 11 to 90) with an equivalent gestational age. In both groups of small-for-dates babies one could find that the chorionic arteries and their trunks were of a lower diameter than those of the villi that were small and that there were sub- chorial deposits of fibrin in both groups. The greater number of placental abnormalities were found in those babies who were severely small-for-dates at a gestational age of between 37 and 39 weeks. The relationship between acute fetal distress and small for dates was analysed. There was little difference in the likelihood of fetal distress between the two groups of small-for-dates babies, but there were differences between both groups and the control group.