Abnormalities in the development of placental vasculature early in pregnancy may result in relative placental underperfusion/hypoxia/ischemia, which then leads to release of antiangiogenic factors into the maternal circulation that alter maternal systemic endothelial function and cause hypertension and other manifestations of the disease (hematologic, neurologic, cardiac, pulmonary, renal, and hepatic dysfunction). However, the trigger for abnormal placental development and the subsequent cascade of events remains unknown