Supplementary Material for: Are Perinatal Events Risk Factors for Childhood Thyroid Autoimmunity?

<p><b><i>Background:</i></b> Environmental and genetic factors possibly trigger thyroid autoimmunity. Studies on perinatal risk factors for childhood thyroid autoimmunity are sparse. <b><i>Objectives:</i></b> The aim was to investigate if perinatal factors, family history of autoimmune diseases, and <i>HLA-DQ</i> genotypes contribute to thyroid autoimmunity in the Diabetes Prediction in Skåne (DiPiS) study. <b><i>Methods:</i></b> Samples from 1,874 ten-year-old children were analyzed for autoantibodies to thyroid peroxidase (TPOAb), thyroglobulin (TGAb), and <i>HLA-DQ</i> genotypes. Information on perinatal events and family history of autoimmunity was gathered prospectively in questionnaires. <b><i>Results:</i></b> Thyroid autoimmunity was found in 6.9% of the children (TPOAb 4.4%, TGAb 5.8%, both autoantibodies 3.3%) and was overrepresented in girls. Prematurity was positively related to TGAb (OR: 2.4, <i>p</i> = 0.003, <i>p</i><sub><i>c</i></sub> = 0.021). Autoimmune diseases in the family increased the risk of thyroid autoimmunity: TPOAb (OR: 2.2, <i>p</i> = 0.012), any autoantibody (OR: 1.7, <i>p</i> = 0.04), and both autoantibodies (OR: 2.2, <i>p</i> = 0.024). A first-degree relative (FDR) with thyroid disease increased the risk for TPOAb (OR: 2.4, <i>p</i> = 0.03) and both autoantibodies (OR: 2.6, <i>p</i> = 0.03), a FDR or sibling with celiac disease increased the risk for both autoantibodies (OR: 3.7, <i>p</i> = 0.03, and OR: 4.8, <i>p</i> = 0.003), a FDR or sibling with diabetes increased the risk for thyroid autoantibody (OR: 3.0, <i>p</i> = 0.01, and OR: 5.4, <i>p</i> = 0.032), and a father with rheumatic disease increased the risk for TPOAb (OR: 15.2, <i>p</i> = 0.017), TGAb (OR: 11.3, <i>p</i> = 0.029), any autoantibody (OR: 9.6, <i>p</i> = 0.038), and both autoantibodies (OR: 20, <i>p</i> = 0.01). <b><i>Conclusions:</i></b> Thyroid autoimmunity was found in 6.9% of the 10-year-old children who were being followed for their risk of type 1 diabetes. No relation to perinatal factors was found, with the exception of a possible association between prematurity and TGAb. Family history of autoimmune diseases increased the risk of thyroid autoimmunity.</p>