title: Down syndrome in British Columbia, 1952-73: incidence and mean maternal age.
abstract: Records of children with Down syndrome (DS) at the BC Health Surveillance Registry were linked to their Birth Registrations to derive maternal ages. Incidence and maternal-age specific rates were calculated for 1952-73. Mean maternal age has declined both for normal and DS children, the latter to a marked degree, so that in 1972-73 80% were born to women under 35 years. Using maternal age of 40 and over as an indication for amniocentesis would only detect 10% of DS children. The crude incidence rate (mean 1.28/1000 livebirths) has not changed appreciably over the study period except for 1969 in which a statistically significant peak occurred. The standarized rate showed an increasing trend but it is not clear whether this was a true biological increase or resulted from better ascertainment.
mesh_terms: D000328:Adult; D000367:Age Factors; D000649:Amniocentesis; D001955:British Columbia; D002648:Child; D004314:Down Syndrome / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008423:Maternal Age; D008875:Middle Aged