OBJECTIVES: The burden of celiac disease (CD) is increasingly recognized as a global problem. However, whether this situation depends on genetics or environmental factors is uncertain. The authors examined these aspects in Sweden, a country in which the risk of CD is generally considered to be high. If environmental factors are relevant, CD risk in second-generation immigrant children should be related to maternal length of stay in Sweden before delivery.

MATERIAL AND METHODS: Linking the Swedish Medical Birth Registry to other national registries, the authors investigated all singleton children (n = 792,401) born in Sweden between 1987 and 1993. They studied the risk of CD in children before age 6 as a function of the mother's geographical region of birth and length of stay in Sweden before delivery using Cox regression models.

RESULTS: In children whose mothers immigrated to Sweden from a country outside of Europe, a maternal length of stay in Sweden of more than 5 years increased the hazard ratio (HR) of CD (1.73, 95% confidence interval (CI) 1.06-2.81). The authors observed a similar result among children born to mothers from a Nordic country outside of Sweden (HR 1.57, 95% CI 0.89-2.75), but a non-conclusive protective effect was observed in second-generation immigrant children from a non-Nordic European country (HR 0.65, 95% CI 0.39-1.09).

CONCLUSIONS: The risk of CD among second-generation immigrants seems to be conditioned by maternal length of stay in Sweden before delivery, suggesting that environmental factors contribute to the variation in CD risk observed across populations.