Mechanism of trophoblast injury and fetal death in CBA/J × DBA/2 mice. As a result of C5a-C5aR interaction on monocytes, TF expression increases. TF expression on monocytes enhances the release of antiangiogenic molecule sFlt-1. sFlt-1 impairs trophoblasts proliferation, reduces placental blood flow, induces oxidative stress, and increased TF expression on trophoblasts leading to fetal death and IUGR. Thrombin can cleave C5, producing more C5a.