Cigarette smoking in pregnancy and risk of pre-eclampsia.

The relationship between smoking in pregnancy and the development of pre-eclampsia has not been well studied. Smoking habits were prospectively evaluated in 117 patients with pre-eclampsia and 468 normotensive control pregnancies. Twenty cases (17.1%) and 120 controls (25.6%) reported smoking at any time during pregnancy. In stepwise multiple logistic regression analysis, smoking in pregnancy was a significant protective factor against the occurrence of pre-eclampsia (adjusted odds ratio = 0.50; 95% confidence interval 0.28-0.80, P = 0.018). On the other hand, a history of pre-eclampsia in previous pregnancies, low (< 6th grade) educational level, a body mass index > 24 and maternal blood group AB were factors independently associated with an increased risk of pre-eclampsia. In conclusion, this study confirms that smoking in pregnancy reduces the risk of pre-eclampsia. However, the harmful consequences of smoking on pregnancy outcome far outweigh this risk reduction.