Yearly and seasonal incidence of mongolism in Quebec

Abstract 2398 births of children with mongolism between 1958 and 1967 in the Province of Quebec were registered—a rate of 1.86/1000 live births. This is somewhat higher than the rates of 1.6 recorded in Britain and 1.5 in Australia. Between 1948 and 1957 the total number of mongoloid births recorded was 1063 (0.9/1000 live births). Underascertainment, especially of mongols who died, was evidently the reason for this low rate. In neither 10‐year period were annual fluctuations in rate found comparable to those observed in Victoria, Australia. There was no evidence of seasonal variation in incidence nor of any increase following epidemics of infectious hepatitis in 1961–63. The findings support those of other surveys in the United States, Britain, and Italy and suggest that the Australian findings were either a chance occurrence or the result of a local phenomenon.