Surface area of chorionic villi of placentas: An index of intrauterine growth restriction of fetuses

Aim: Histomorphometric studies of placentas from idiopathic intrauterine growth restricted (IUGR) fetuses as well as normal-weight (control) fetuses were performed to determine surface area of chorionic villi (mostly terminal and few intermediate) using stereological technique. The results were compared to determine the difference in the values of surface area of chorionic villi, and to establish any relationship between placental histomorphometric changes and IUGR. Methods: Placentas from fifty (50) full-term, uncomplicated deliveries were collected; twenty eight (28) of them were associated with IUGR babies and twenty two (22) were from normal-weight babies. Placental weights and volumes were measured. Pieces of placental tissues were formalin-fixed, processed and embedded in paraffin. Seven-micron sections were cut and stained with HE stain. Histomorphometric and stereological studies were performed. Results: IUGR placental weights and volumes were lower than those of controls. Surface areas of villi of IUGR placentas had a mean of 8.19 m(2) (SD +/- 2.88). For control placentas, the mean was 10.02 m(2) (SD +/- 1.83). The mean value of the surface area of villi of the IUGR group was significantly lower than that of the control group. Conclusion: These findings pointed to a defect in the normal interaction between trophoblast and maternal tissue, leading to a reduced surface area of villi. Because the surface area of the villi presents the interface between maternal and fetal circulation, its reduction might be the cause of idiopathic intrauterine growth restriction.