Down's syndrome in Western Australia: mortality and survival.

An epidemiological investigation of 231 cases of Down's Syndrome born in Western Australia between 1966 and 1976 confirmed the importance of congenital heart disease as a determinant of early mortality. An unexplained and hitherto unreported high incidence of Sudden Death in Infancy Syndrome if survival rates with those of other investigators show, that mortality amongst cases of Down's Syndrome with no congential heart defect has decreased and longevity is no longer a rate occurrence. As a result of these changes, and despite a demonstrable fall in the incidence of Down Syndrome in Western Australia, the prevalence of the condition is expected to rise.