European Journal of Epidemiology

, Volume 22, Issue 7, pp 467–472

Smoking and environmental iodine as risk factors for thyroiditis among parous women

  • Maria Rosaria Galanti
  • Sven Cnattingius
  • Fredrik Granath
  • Annika Ekbom-Schnell
  • Anders Ekbom
Review Paper



To elucidate whether exposure to some environmental factors, i.e. cigarette smoking and iodine deficiency influence the risk of thyroiditis.


We identified a cohort of 874, 507 parous women with self-reported information on smoking during pregnancy registered in the Swedish Medical Birth Registry from September 1983 through December 1997. Hospital diagnoses of thyroiditis (n = 286) and hypothyroidism (n = 690) following entry into the cohort were identified by record-linkage with the national Inpatient Registry. The hazard ratio (HR) of smokers compared to non-smokers and the corresponding 95% confidence limits (CL) were estimated by Cox regression.


Smoking was inversely associated with risk of overt thyroiditis (adjusted HR = 0.72; CL = 0.54–0.95), even when diagnoses of primary hypothyroidism were included. However, a diagnosis of thyroiditis within 6 months from a childbirth was positively associated with smoking (adjusted HR = 1.88; CL = 0.94–3.76). Being born in areas of endemic goiter was not associated to hospital admission for thyroiditis. Thyroiditis patients who were smokers had more often than non-smokers a co-morbidity with other autoimmune disorders.


Smoking may increase the risk of thyroiditis occurring in the post-partum period and influence the clinical expression of other thyroiditis, especially when occurring as part of a polymorphic autoimmune disease.


Thyroiditis Hypothyroidism Cigarette smoking Iodine deficiency Cohort study Sweden 



Autoimmune thyroid disease


Confidence limits


Hazard ratio


Hashimoto thyroiditis


International classification of diseases and causes of death


Post-partum thyroiditis


Thyroid peroxidase antibodies


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Maria Rosaria Galanti
    • 1
    • 2
  • Sven Cnattingius
    • 3
  • Fredrik Granath
    • 1
  • Annika Ekbom-Schnell
    • 4
  • Anders Ekbom
    • 1
  1. 1.Clinical Epidemiology Unit, Department of MedicineKarolinska InstitutetStockholmSweden
  2. 2.Stockholm Centre for Public Health/Tobacco PreventionStockholmSweden
  3. 3.Department of Medical Epidemiology and BiostatisticsKarolinska InstitutetStockholmSweden
  4. 4.Department of MedicineUppsala University HospitalUppsalaSweden

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