The antiphospholipid syndrome (APS) is characterized by recurrent fetal loss, intrauterine growth restriction, and vascular thrombosis in the presence of antiphospholipid (aPL) Abs. Our studies in a murine model of APS induced by passive transfer of human aPL Abs have shown that activation of complement and recruitment of neutrophils into decidua are required for fetal loss, and emphasize the importance of inflammation in aPL Ab-induced pregnancy loss. In this study, we examine the role of TNF-α in pregnancy complications associated with aPL Abs in a murine model of APS. We show that aPL Abs are specifically targeted to decidual tissue and cause a rapid increase in decidual and systemic TNF-α levels. We identify the release of TNF-α as a critical intermediate that acts downstream of C5 activation, based on the fetal protective effects of TNF-α deficiency and TNF blockade and on the absence of increased TNF-α levels in C5-deficient mice treated with aPL Abs. Our results suggest that TNF-α links pathogenic aPL Abs to fetal damage and identify TNF blockade as a potential therapy for the pregnancy complications of APS.