In France, the incidence of PE is estimated to range between 1 and 3% in the nuliparous and between 0.5 and 1.5% in the multiparous women. Factors associated with the development of PE are of various types. Studies conducted on families affected by PE suggest the existence of a genetic component to the disease, even though the association between PE and certain genes, allotypes and polymorphisms are still under scrutiny. The hypotheses suggesting an immunological mechanism is supported by several arguments. Indeed, being nuliparous, changing partner, insemination with donor semen are factors associated with the development of PE whereas pre-exposition to the father's sperm bears protection. Some factors qualified as physiological are also associated with the occurrence of PE although no clear pathophysiological explanation can be put forward. These are being a mother of African descent, an increase in the mothers' age or herself being born prematurely. Some gestational incidents are also associated with the occurrence of PE: multiparity, a congenital defect affecting the foetus, UTI. Similarly, some pre-existing conditions of the mother are associated with PE, i.e. chronic hypertension, kidney disease, obesity and diabetes mellitus. Several well designed epidemiological studies confirm that tobacco consumption is itself associated with a 20 to 50% reduction in the development of PE, although being itself associated with an increase in other vascular gestational complications such as retroplacental haemorrhage and IUGR. Living conditions and stress, especially at work are also associated with the occurrence of PE. All these identified risk factors by far do not account for all the reported cases of PE and do not bear sufficient positive or negative predictive value.
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