Placenta messages to the mother: not just debris.

See related article, pp 256–264 Preeclampsia is a major pregnancy complication, affecting 5% of all pregnancies, that is responsible for >50 000 maternal deaths annually. The only cure for preeclampsia is delivery, which, in early onset cases, will be a premature one. The adverse acute and chronic clinical impact on the mother and the child may be severe; the cost to society is immense. Preeclamptic women are at increased risk of cardiovascular disease later in life. The in utero environment also has significant influence on lifelong health of the offspring, and children of preeclamptic pregnancies run increased risk for adolescent hypertension and adult cardiovascular disease. Preeclampsia is characterized by new hypertension and proteinuria developing in the second half of the pregnancy. The exact pathogenesis of the disease is far from understood, but it is accepted today that the placenta itself plays an essential role. Oxidative stress, circulating placental-derived factors, immunologic factors, nutrition, physical activity, and genetic variance are all important. A 3-stage preeclampsia model has been proposed where the last stage represents the clinical illness.1 Dysregulated immunologic factors (stage 1) underlying defective placentation with reduced invasion of fetal extravillous trophoblast cells and reduced remodeling of maternal uteroplacental spiral arteries (stage 2) are initial pathophysiological events. An unfavorable uteroplacental circulation ensues, with enhanced oxidative and endoplasmic reticulum stress and increased release of trophoblast-derived factors to the maternal circulation, which are thought to contribute to an excessive maternal inflammatory response and endothelial dysfunction. This induces the maternal clinical signs of preeclampsia with hypertension and proteinuria (stage 3). Older clinicians will recall that preeclampsia used to be called “toxemia of pregnancy,” because clinicians believed that a circulating toxin was poisoning the mother. Because the condition went away after delivery, the conclusion that the poison comes from the placenta would appear most reasonable. …