Background: Pregnant women with female fetuses have higher maternal serum human chorionic gonadotropin (hCG) levels than pregnant women with male fetuses. Ki-67, a cell proliferation and activity marker, is confined mostly in the nuclei of villous cytotrophoblasts of the human placenta. In this study, we examined the effect of fetal gender on the cytotrophoblast cell activity in human term placenta, with special regard to maternal serum and cord blood hCG levels.
Methods: Thirty-four uncomplicated, singleton, term pregnancies (17 male and 17 female fetuses) were recruited in the study. hCG was measured in maternal peripheral serum and umbilical cord blood. Placental samples were collected in each patient during the cesarean section. Cytotrophoblast cell activity was measured by using immunohistochemistry for Ki-67 antigen. Ki-67 staining index values of the cytotrophoblasts were compared between the female and male placentas.
Results: Maternal serum and cord blood hCG levels were higher in pregnant women with female fetuses than in those carrying male fetuses. There was no sex difference in Ki-67 immunostaining rates of the cytotrophoblast cells. There was no correlation between maternal serum and cord blood hCG levels and Ki-67 staining index values of the cytotrophoblast cells.
Conclusions: The difference in maternal serum and cord blood hCG levels in correlation with the fetal gender is not associated with cytotrophoblast cell activity in the human term placenta. The gender of the fetus does not seem to affect the regulation of cytotrophoblast cell proliferation.