Abstract
The Canadian Congenital Anomalies Surveillance System monitors birth defects reported for stillborns, newborns and infants during the first year of life. Data are available through the 1980s and early 1990s for Ontario, Manitoba and Alberta, and since 1984 for an additional four provinces. Fiftyseven routine monitoring categories and 15 summary categories were examined for temporal trends. Comparing the period 1979–1981 with 1991–1993, the reported birth defect case birth prevalence increased by 0.2% and the total birth defects birth prevalences by 2.5%. The birth prevalence of central nervous system defects decreased by 8.2%; the reported birth prevalence increased for congenital heart defects by 41%, urinary defects by 127%, Down syndrome by 13% and other chromosomal defects by 47%. Further investigation of individual defects would be required to evaluate the degree to which changes in reported birth prevalence reflect changes including the availability and use of specific diagnostic procedures. The work highlights the need to expand the surveillance system to include all affected pregnancies where an anomaly has been detected antenatally.
Résumé
Le Système canadien de surveillance des anomalies congénitales recense les cas de malformation congénitale déclarés chez les mortnés, les nouveau-nés et les nourrissons pendant la première année de vie. Des données sont disponibles pour toutes les années 1980 pour Ontario, Manitoba et Alberta et depuis 1984 pour quatre autres provinces. Pour déterminer les tendances temporelles, on a examiné 57 catégories de surveillance systématique et 15 catégories générales. Il ressort de la comparaison des périodes 1979–1981 et 1991–1993 que la prévalence des cas de malformation congénitale déclarés à la naissance a augmenté de 0,2% et que la prévalence totale des naissances avec malformations congénitales a augmenté de 2,5%. La prévalence des naissances avec anomalies du système nerveux central a diminué de 8,2%; la prévalence des naissances déclarées a augmenté pour les malformations cardiaques congénitales (41%), les malformations du système urinaire (127%), le syndrome de Down (13%), et d’autres anomalies chromosomiques (47%). Il faudra pousser les études sur chaque anomalie afin de déterminer dans quelle mesure les changements enregistrés dans la prévalence des naissances déclarées reflètent des changements tels que la disponibilité et l’utilisation de méthodes diagnostiques précises. Cet ouvrage souligne le besoin d’étendre le champ d’activité des systèmes de surveillance afin d’y inclure toutes les grossesses où une anomalie fut détectée durant la période anténatale.
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