The Two Stage Model of preeclampsia proposes that a poorly perfused placenta (Stage 1)
produces factor (s) leading to the clinical manifestations of preeclampsia (Stage 2). Stage 1
is not sufficient to cause the maternal syndrome but interacts with maternal constitutional
factors (genetic, behavioral or environmental) to result in Stage 2. Recent information
indicates the necessity for modifications of this model. It is apparent that changes relevant to
preeclampsia and other implantation disorders can be detected in the first trimester, long …