Citation Kwak-Kim J, Park JC, Ahn HK, Kim JW, Gilman-Sachs A. Immunological modes of pregnancy loss. Am J Reprod Immunol 2010
During the implantation period, a significant portion of embryos are lost and eventually less than half of clinically established pregnancies end as full-term pregnancies without obstetrical complications. A significant portion of these pregnancy losses is associated with immune etiologies, including autoimmune and cellular immune abnormalities. Although an autoimmune etiology such as anti-phospholipid antibodies (APAs) has been reported to induce placental infarct and thrombosis at maternal–fetal interface, APAs induce inflammatory immune responses as well. Inflammatory immune responses, such as increased proportions of NK cells and Th1/Th2 cell ratios in peripheral blood are related to recurrent pregnancy losses and multiple implantation failures. Systemic and local inflammatory immune responses seem to be induced by activation of Toll-like receptors with infectious agents, fetal cell debris, or gonadotropin-releasing hormone agonist, etc. Cellular activation of T and NK cells leads to pro-inflammatory cytokine storm and consequently, placental infarction and thrombosis. Potential application of anti-inflammatory therapeutic agents for the prevention of pregnancy losses should be explored further.