Updated project metadata. Patients who are diagnosed with thrombotic thrombocytopenic purpura (TTP) during pregnancy are at increased risk of maternal and fetal complications including fetal demise. We present a case of a 32-year-old G3P0 (gravida 3, para 0) who presented at 20 weeks’ gestation with a new diagnosis of congenital TTP (cTTP) and fetal demise. Methods: We describe the pathophysiology of pregnancy complications in a patient with cTTP using platelet procoagulant membrane dynamics analysis and quantitative proteomic studies, compared to 4 pregnant patients with gestational hypertension, 4 pregnant patients with preeclampsia and 4 healthy pregnant controls. Results: The cTTP patient had increased P-selectin, tissue factor expression, annexin-V binding on platelets and neutrophils, and localized thrombin generation, suggestive of hypercoagulability. Among 15 proteins that were upregulated, S100A8 and S100A9 were distinctly overexpressed.Conclusions: There is platelet-neutrophil activation and interaction, platelet hypercoagulability and proinflammation in our case of cTTP with fetal demise.