The unexpected beneficial role of smoking in preeclampsia

We have recently investigated the association between the risk of developing PE and clinical, hemostatic, inflammatory and genetic parameters of 108 severe preeclamptic women. A multivariate logistic regression analysis was performed to assess what variables are independent risk factors for PE. Univariate analysis was performed including the variables in age, smoking condition, multiple pregnancy, blood group, phenotypes and alleles of IL-4, IL-5, IL-10, IL-6, IL-8, IL-12, IL-1β, IFN-γ, TNF-α, and the plasma levels of FVII, FVIIa, FVIIa-AT, FVIII, FVW, ADAMTS13, D-Di, PAI-1, ADMA. Those variables whose P < 0.20 (smoking, multiple pregnancy, blood group, phenotype IL-6, IFN-γ allele, IL-10 allele and FVII) were selected to the multivariate logistic regression. In the final model, only FVII, IFN-γ allele and smoking were independently associated to severe PE (P < 0.0001, P < 0.0001 and P = 0.008, respectively). Increased FVII plasma levels and IFN-γ "T" allele were associated to an increased probability of developing PE (OR 1.001, 95% CI [1.001-1.002], and OR 4.81 95% CI [2.42-9.60], respectively). On the other hand, smoker status was associated with a 4.72 decreased chance of PE occurrence (OR 4.72, 95% CI [1.51-14.75]). In this article we also reviewed the studies that investigate the risk of PE in pregnant women who smoked, as well as the effect of tobacco extract in cells or animal models. The hypotheses proposed to explain the biological mechanism by which smoking during pregnancy reduces the risk of PE was also discussed.