© 1972 Oxford University Press
research-article |
Seasonal Influences on the Risk of Cardiac Malformation: Nature of the Problem and Some Results from a Study of 10,077 Cases
1 Department of Cardiology and Research Institute of the Hospital for Sick Children, University of Toronto Toronto 5, Canada
2Department of Epidemiology and Biometrics, School of Hygiene, University of Toronto Toronto 5, Canada
3Department of Epidemiology and Biometrics, School of Hygiene, University of Toronto Toronto 5, Canada
Requests for reprints may be addressed to Dr. Rose.
Rose, V. (Dept. of Cardiology and Research Institute of the Hospital for Sick Children, University of Toronto,Toronto 5, Canada), Hewitt, D., and Mimer, J. Seasonal influences on the risk of cardiac malformation. Int. J. Epid.1972, 1 : 235–244.
Birth date and diagnostic data on 10,077 cases of congenital heart disease studied at the Hospital for Sick Children, Toronto, were used in Part I to illustrate some problems of epidemiological method that require further attention in the search for seasonal influences on malformation. Among the birth-rate patterns noted in the Toronto data are:
(a) A slight but significant excess of congenital heart disease as a whole in the fall and winter, rates for October-March averaging 6–7 per cent higher than those for April-September.
(b) A much more strongly marked excess of cases with transposition of the great arteries during August-January.
(c) Distinct seasonal peaks in the fall (for males) and spring (for females) of cases with pulmonary valve stenosis.
(d) A stronger correlation for males than females between rubella exposure and patent ductus arteriosus.
(e) Significant changes from year to year in the percentage of males among newborn cases of congenital heart disease as a whole.
The seasonal pattern recently reported from New England for coarctation of the aorta cannot be detected in Ontario.
Received 8 May 1972