Histologic examination of the placenta in the growth-retarded fetus.

This investigation was undertaken to determine whether histologic examination of the placenta contributed to a better understanding of the cause of intrauterine fetal growth retardation. Placentas were examined of 151 liveborn infants whose birthweights were in the lower 10th percentile for gestational age. One or more histologic aberrations were found in 139 (92%) cases, in contrast to one or more antenatal risk factors (primarily hypertension) in 77 (51%) cases or a gross placental abnormality (primarily abruption) in 46 (30%) cases. Compared with placentas belonging to appropriately sized fetuses, histologic signs of uteroplacental vascular insufficiency, chronic inflammation, and hemorrhagic endovasculitis were significantly more common in the study group. The primary histologic condition was supportive of prior clinical impressions in 61 (40%) cases, contradictory in 23 (15%) cases, or solely contributory to explaining the growth retardation in 55 (36%) cases. Placental histologic examination may clarify a cause for delayed fetal growth, especially after a normotensive pregnancy.