Effect of the mode of conception on incidences of apoptotic and proliferative cells in full term human placentas

Abstract

OBJECTIVES: To compare the cell dynamics of term placental tissue in pregnancies conceived by in-vitro fertilization (IVF) and embryo transfer with spontaneous pregnancies. METHODS: Placental samples were obtained from singleton term IVF pregnancies (n=25) and singleton term spontaneous pregnancies (n=30). Ethical approval was obtained from the Faculty of Medicine, The University of Hong Kong. The incidence of apoptotic and proliferative cells was determined by the TUNEL method and immunohistochemistry for Ki-67 antigen. RESULTS: In IVF group maternal age [36(26-40)] was significantly (p<0.01) greater than in the spontaneous pregnancies [32(20-38)]. There was no difference in maternal-height, pre-pregnancy weight, weight gain, gestational age at delivery, placental weight and infant birthweight between the two groups. The TUNEL-positive cells were principally syncytiotrophoblast with clustering of the nuclei. Incidence of TUNEL-positive cells in IVF group was [0.15%(0.02-0.87)] similar to that in the spontaneous group [0.13%(0.00-0.68)]. Ki-67 positive index in IVF and spontaneous pregnancies was cytotrophoblast 0.51%(0.02%-2.50%) vs 0.25%(0.04% - 0.92%), Stroma 0.11% (0.02% - 0.30 %) vs 0.05% (0.00% - 0.14%) and endothelial cells 0.20%(0.01%-1.51%) vs 0.02% (0.00% -0.12%) of the respective cell type. The incidence of each placental cell type, stained Ki-67 positive was significantly higher (p<0,05) in IVF placentas (p<0.05, Mann-Whitney U test). Results are expressed as median (range). CONCLUSION: The results denote distinct differences in cell dynamics between IVF and control pregnancies. However, the cellular and molecular mechanisms mediating changes in the placenta of IVF conceptions remain to be determined.