Flow chart depicting participation in the study. Numbers of children and percentages are given in the boxes. In total, 714 children with suspected celiac disease (abbreviated as CD in the figure) were reported to the register. Consent to participate was obtained for 475 cases below two years of age with a celiac disease diagnosis based on three consecutive small intestinal biopsies. Boxes with dotted lines indicate excluded children. Two referents to each case were randomly selected after matching criteria were fulfilled. Grey shaded areas indicate invited infants and those included in the final analysis.