Pregnancy is a unique symbiotic union between mother and fetus which contradicts many of the general rules of immunology. The maternal immune system reacts towards the foreign tissue, but instead of triggering rejection, it tolerates, supports and regulates its development. The immunological mechanisms allowing the fetus to grow and survive are complex and may be affected by internal and external factors which may result in pregnancy disorders including infertility, abortions and preeclamptic disease. In this book leading scientists present the latest findings on the physiological mechanisms required for successful pregnancies, and the pathologies that may be caused by a disturbance of these mechanisms. The regulation of maternal NK cells, T cells and dendritic cells through hormones, cytokines, the complement system and HLA as well as other cell surface molecules is described in detail. The knowledge gained from the immunoregulation of pregnancy is also important in other fields of immunology and may lead to new therapeutic concepts in posttransplantation or allergy therapies, or in the fight against cancer. This volume provides fascinating insights for those readers who are not yet familiar with the immunology of reproduction while it also serves to update specialists on the most recent findings in the field.