Alloimmune causes of recurrent pregnancy loss.

Recurrent pregnancy loss is a vexing problem facing many couples. Some authorities have suggested that idiopathic recurrent pregnancy loss is alloimmune in nature. Suggested mechanisms include the presence of cytotoxic antibodies, absence of maternal blocking antibodies, inappropriate sharing of human leukocyte antigens, and disturbances in natural killer cell function and distribution. Proposed therapies for so-called alloimmune-related pregnancy loss include leukocyte immunization and intravenous immune globulin. Unfortunately, neither has been successful in well-designed trials and both are expensive. Although alloimmune disturbances may be responsible for some idiopathic recurrent pregnancy loss, the pathophysiology is far from certain and there is currently no clinical indication for immunotherapy.