Dysregulation of hCG may lead to preeclampsia. In normal pregnancy, functional hCG, optimum expression of IL-10, and the temporal appearance of uNK and Tregs contribute to immune tolerance and angiogenesis. Dysregulated hCG due to altered structure/glycosylation may influence expression of IL-10, IDO and appearance of Tregs and uNK cells resulting in pregnancy complications such as preeclampsia. hCG: human chorionic gonadotropin, IL-10: interleukin-10, IDO: indoleamine 2,3-dioxygenase, uNK : uterine natural killer cells, Treg: regulatory T cells, ET: endovascular trophoblasts.