Preeclampsia is a pregnancy complication with serious consequences for mother and infant. The disorder is diagnosed by gestational hypertension and proteinuria but is far more than pregnancy induced hypertension. Preeclampsia is proposed to occur in 2 stages. Stage 1 reduced placental perfusion is postulated as the root cause and to lead to the maternal syndrome, Stage 2. Why perfusion is reduced, how this translates to a maternal disease in some but not all women and what is the linkage of the 2 stages are topics of intense study. In the last decade such studies have provided valuable insights into pathophysiology that now guide ongoing clinical trials.