Table 1

Distribution of the number of children and the number of observations for the two groups of Swedish children with Down's syndrome

Group 1Group 2Total
Group 1: all children living in specified regions of Sweden.
Group 2: children with Down's syndrome recruited from an appeal.
    No. of children12083203
    No. of observations13635401903
    No. of children8368151
    No. of observations9565711527