ABSTRACT
The occurrence of Down's syndrome in British Columbia during the period 1972-75 is analyzed with respect to maternal age distribution. This period is compared with previously studied periods. No marked trends are evident in the various age group-specific rates studied. The significance of these findings is discussed in connection with a possible role of environmental nutagens in induction of Down's syndrome and the maternal age effect.
Subject(s)
Down Syndrome/epidemiology , Maternal Age , Adult , Age Factors , British Columbia , Down Syndrome/etiology , Environmental Exposure , Female , Humans , Middle Aged , Mutagens , PregnancyABSTRACT
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.
Subject(s)
Down Syndrome/epidemiology , Maternal Age , Adult , Age Factors , Amniocentesis , British Columbia , Child , Female , Humans , Middle AgedSubject(s)
Disabled Persons , Registries , Adult , British Columbia , Child , Confidentiality , Follow-Up Studies , Genetic Counseling , Humans , Population SurveillanceABSTRACT
The incidence of PKU in British Columbia in the 1950-1971 period is 1/18,750 which corresponds to that found in two other Canadian studies.(2, 3) Evidence is presented which shows a trend toward a decline in incidence; however, this is not statistically significant. There is a preponderance of male cases in all age groups.
