The objective was to investigate whether selected perinatal factors, as indicators of perinatal exposures, are associated with the risk of type 1 diabetes in children. Specifically, we tested whether maternal preeclampsia, Rhesus-immunization, induced labor, cesarean section, and multiple birth were associated with incidence of type 1 diabetes. A cohort study was designed by linking records of the Medical Birth Registry and the National Childhood Diabetes Registry of Norway. Live births in the study period were followed for a maximum of 15 y and contributed 8,166,731 person-years between 1989 and 1998. Altogether, 1824 cases of type 1 diabetes diagnosed between 1989 and 1998 were identified within the cohort. There was a suggestive, but nonsignificant, increase in risk of type 1 diabetes associated with Rhesus-immunization. Maternal preeclampsia, cesarean section, and the other perinatal factors investigated in this study were not significantly associated with incidence of type 1 diabetes in the children. Previous indications that cesarean section and preeclampsia are associated with type 1 diabetes were not supported by this large study. The majority of routinely recorded perinatal factors are only weakly associated with type 1 diabetes, or not at all.
