Rethinking preeclampsia: six paradigm shifts in placental pathophysiology for maternal-foetal medicine

Preeclampsia affects 2-4% of pregnancies worldwide and remains a leading contributor to maternal and perinatal morbidity and mortality. The prevailing framework, anchored in defective second-trimester spiral-artery remodelling, placental hypoxia, and antiangiogenic imbalance, continues to guide screening, prediction, and prevention. Evidence accumulated over the past 5 years, however, indicates that several pillars of this framework may require revision. This narrative review synthesises six inter-related paradigm shifts emerging principally from the research programme of the Huppertz group at the Medical University of Graz between 2020 and 2026, and situates them against contemporaneous mainstream formulations. The six shifts addressed are: first-trimester villous origins rather than second-trimester deep-placentation failure; intervillous hyperoxia rather than placental hypoxia in early-onset disease; metabolic and glycocalyx-based pathogenesis rather than pure angiogenic imbalance; the placenta as an endogenous exposome via extracellular vesicles; steroid imbalance coupled with alternative renin-angiotensin-leptin signalling; and reduced immune tolerance together with dynamic in vitro models that challenge inferences drawn from static explants. Collectively, these shifts reframe preeclampsia as a first-trimester syndrome of villous trophoblast dysregulation that propagates to maternal endothelial injury through multiple, partly redundant pathways. They suggest that maternal-foetal medicine may benefit from earlier, multimodal risk assessment, from biomarker panels that capture senescence, metabolic and extracellular vesicle signatures, and from a more cautious mechanistic interpretation of the soluble fms-like tyrosine kinase 1 to placental growth factor ratio, whilst acknowledging its established short-term clinical utility for triage. Several of these propositions, particularly those concerning intervillous hyperoxia and alternative renin-angiotensin-leptin signalling, still require independent replication in cohorts beyond the originating research environment before clinical translation. The six shifts do not individually overturn the two-stage framework; collectively they relocate the initiating lesion, broaden the signalling vocabulary, and argue for translation into first-trimester multimodal panels that extend beyond current angiogenic and Doppler measures.