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Cyclic Variations of Twin Births at Isle-aux-Coudres: A Case/Control Approach

Published online by Cambridge University Press:  01 August 2014

P. Philippe*
Affiliation:
Department of Social and Preventive Medicine, Faculty of Medicine, University of Montreal, Canada
*
Department of Social and Preventive Medicine, University of Montreal, Pav. Marguerite d'Youville, Montreal H3C 3J7, QC, Canada

Abstract

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Twins and singletons were matched for several confounding factors. The monthly distribution of twin births and that of singleton births were compared with a uniform allocation of births over the year. Opposite seasonal variations emerged that were confirmed by a case/control comparison. Twins occurred more often in winter and early spring while singletons proved to be relatively few; singleton peaked in the fall season when the risk of a twin birth was low. These trends held across maternal age at birth and the time period of birth. Results suggest that the conception of a twin pair is higest in spring and early summer and lowest in winter. The role of sunlight in the twinning liability is discussed along with the role of sexual intercourse. That twin-prone mothers are usually more fecund in spring and early summer is a distinct possibility.

Type
Research Article
Copyright
Copyright © The International Society for Twin Studies 1987

References

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