Endothelial cell injury, with subsequent vasospasm, platelet activation, unbalanced prostacyclin-thromboxane ratio, and decreased release of endothelium-derived relaxing factor, play a central role in the pathogenesis of several disorders such as preeclampsia, hemolysis, elevated liver enzymes, and low platelet syndrome, thrombotic thrombocytopenic purpura, hemolytic uremic syndrome, acute fatty liver of pregnancy, and acute renal failure. It is possible that all these diseases are part of a spectrum of the same illness. Although the cause remains unknown, the pathophysiology of these diseases is important for an early diagnosis. Differential diagnosis is often difficult due to the overlap of these syndromes. The purpose of this review is to clarify the differences and similarities among these pregnancy-related complications.