consecutive pregnancy losses before 20 weeks of gestation (with the same partner) (2). Despite several well established etiologic factors, the cause of recurrent pregnancy loss (RPL) cannot be determined in almost 50% of cases. It was suggested that these unexplained RPLs might be due to immunologic factors (3). A successful pregnancy depends on tolerance of a semiallogenic embryo/fetus by the maternal immune system. It is believed that this tolerance depends on the interactions of various cytokines excreted by maternal and fetal cells at the site of implantation. A shift from proinflammatory T-helper (Th)1 cell-dependent cytokines to
Th2-dependent anti-inflammatory cytokines seems to be a characteristic of a successful pregnancy.

consecutive pregnancy losses before 20 weeks of gestation (with the same partner) (2). Despite several well established etiologic factors, the cause of recurrent pregnancy loss (RPL) cannot be determined in almost 50% of cases. It was suggested that these unexplained RPLs might be due to immunologic factors (3). A successful pregnancy depends on tolerance of a semiallogenic embryo/fetus by the maternal immune system. It is believed that this tolerance depends on the interactions of various cytokines excreted by maternal and fetal cells at the site of implantation. A shift from proinflammatory T-helper (Th)1 cell-dependent cytokines to
Th2-dependent anti-inflammatory cytokines seems to be a characteristic of a successful pregnancy.