Smoking and celiac disease: A population-based cohort study

Background & Aims: Earlier studies indicate a protective effect of smoking against celiac disease (CD), but have been based on small numbers and retrospective collection of smoking data. Methods: We linked the Swedish national inpatient register and the medical birth register to study the association between smoking status during pregnancy and CD (diagnosed or undiagnosed at delivery) in women who were pregnant from 1983 to 2001. We adjusted for civil status, age, and year when smoking data were collected. We identified 873 cases of CD (636 diagnosed and 237 undiagnosed). Results: Of 249,967 smokers, 67 (.27%) had undiagnosed CD (vs 170 of 794,912 nonsmokers [.21%]) (odds ratio [OR], :1.25; 95% confidence interval [Cl],.94-166; P =.118). Point estimates remained unchanged when adjusting for civil status, age, and year of smoking data collection (adjusted OR [AOR], 1.25; 95% Cl AOR,.94-1.67). There were no associations between smoking and future (undiagnosed at delivery) CD when we adjusted for potential confounders and stratified for comorbidity or time to diagnosis (<5 vs >= 5 y after infant birth). In women with diagnosed CD, smoking was more common than in women who never had a diagnosis of CD (AOR, :1.36; 95% Cl AOR, 1.12-1.64; P =.002). Conclusions: Smoking seems to have little effect on the risk for future CD in pregnant women.