Objective: To examine the impact of women's quitting smoking during early and late pregnancy on their risk of preeclampsia and on birth outcomes.
Methods: We analyzed data from a case-control study of 86 preeclamptic women and 239 controls at three hospitals in Quebec between January 2003 and March 2006.
Results: Compared with never having smoked, early smoking cessation, i.e., quitting before 20 weeks' gestation, was not associated with a reduced risk of preeclampsia (adjusted OR 1.03; 95% CI 0.42-2.60). Both late smoking cessation (quitting after 20 weeks of gestation) and persistent smoking (smoking before and during pregnancy) were associated with a non-significant reduction in the risk of preeclampsia (aOR 0.78; 95% CI 0.12-5.02 for late quitting and aOR 0.62; 95% CI 0.16-2.37 for persistent smoking). However, persistent smoking was associated with an increased risk of other adverse pregnancy outcomes, such as low birth weight (aOR 10.2; 95% CI 2.49-41.8) and preterm birth (aOR 3.59; 95% CI 1.06-12.1).
Conclusion: Although late quitting and persistent smoking may be associated with a decreased risk of preeclampsia, the benefit of early smoking cessation on pregnancy outcome is evident.