Figure 1. The two-stage model of preeclampsia.
It is proposed that the initiating insult in preeclampsia is a relative reduction of the perfusion of the placenta, Stage 1. This insult leads to the generation of materials (arrow) that act on the maternal constitution to result in the maternal pathophysiology of preeclampsia, Stage 2. Reprinted from Roberts & Hubel (2009), with permission from Elsevier.