Berthold Huppertz
Preeclampsia is a pregnancy-specific syndrome with clinical symptoms including hypertension and a multitude of organ dysfunctions of the pregnant woman. So far, the etiology of preeclampsia is unclear, and a vast number of hypotheses has been created to explain the onset and pathophysiological pathways of the syndrome. Unfortunately, all of the theories suffer from the fact that they cannot explain the whole spectrum of symptoms and timing during pregnancy. Therefore, this review tries to elucidate published data that offer the opportunity to decipher earlier stages of the syndrome. Data will be listed and merged that have been obtained prior to pregnancy or during the first trimester of pregnancy from women developing preeclampsia later in this pregnancy. This allows looking into alterations of placental cells and tissues occurring long before onset of clinical symptoms. The respective data clearly shows changes of the villous trophoblast already during and at the end of the first trimester in all types of preeclampsia. This set of data may help in generating new ideas to allow the creation of new hypotheses that may better explain the diversity of the syndrome.