Vascular factors in the pathogenesis of pre-eclampsia: recent findings

Normal, rigid and fibrotic utero-placental arteries are resistant to the action of circulating vaso-motor substances. In contrast, the persistence and the hyperplasia of smooth muscle fibres result in a reduced flow in the intervillous compartment and a sensitivity of the vessels to vaso-constrictor substances. These lesions, which develop after the twentieth week, provide the necessary conditions for the subsequent development of the characteristic vicious cycles of eclampsia.