Background: Second to Finland, Sweden has the world’s highest incidence of type 1 diabetes. Experiences of serious life events have retrospectively been shown to constitute a risk factor for the development of this disease, probably via the biological stress response. Parenting stress and maternal attachment insecurity are other important sources of stress in early childhood. Psychological stress increases the need for insulin and may induce insulin resistance, which might add extra pressure on the insulin-producing beta cells in the pancreas (beta-cell stress). The aim of the current thesis was to propose and start investigating a stress hypothesis – namely that psychological stress may induce insulin resistance leading to beta-cell stress, which could trigger an autoimmune reaction towards beta-cells in genetically predisposed children. When all the beta cells have been destroyed, insulin can no longer be produced in the body and type 1 diabetes becomes manifest. Methods: Families from the prospective population-based ABIS-project, which follows approximately 17 000 children, participated in the empirical studies of the current thesis. The mothers completed questionnaires, including various measures of psychological stress (e.g. parenting stress and experiences of serious life events) and socio-demographic background, at the birth of the child and when the child was 1 as well as 2.5 years of age. Maternal attachment insecurity was assessed with the Adult Attachment Interview. Blood samples drawn from the children at 1 and 2.5 years of age were analyzed for type 1 diabetes-related autoantibodies towards Tyrosine phosphatase (IA-2) and Glutamic Acid Decarboxylase (GAD). Findings and Conclusions: Parenting stress and experiences of serious life events like divorce and maternal exposure to violence were associated with the induction of diabetes-related autoimmunity in early childhood, possibly via insulin resistance and beta-cell stress. The risk of developing diabetesrelated autoimmunity after parental divorce or mothers’ exposure to violence was about threefold. None of the results were explained by any of the potential confounding factors analyzed. These results support and strengthen the stress hypothesis, which warrants further investigation. Mothers’ attachment insecurity was not associated with the induction of diabetes-related autoimmunity in their infants. However, this lack of association was perhaps due to methodological constraints. The vast majority of the parents were calmed or unaffected concerning their participation in the ABIS-project, suggesting that large-scale medical screening-projects in the general population are not in themselves a cause for worry and can be performed without causing increased anxiety. / On the day of the public defence the working title of article III was: Psychosocial correlates of parenting stress, lack of support and lack of confidence – A study of all babies in Southeast Sweden (ABIS). The status of article IV was: Manuscript to be submitted shortly; the status of article V was: Manuscript in preparation.