Inizan Juliette and Bouvier-Colle Marie-Hélène. - Seasonality in the Sudden Death Syndrome among Infants. 20 % of infant deaths in France are attributed to sudden infant death syndrome, characterized by ill-defined symptoms and morbid states. This proportion has recently increased in a number of industrialized countries for no apparent reason, and it is difficult to determine whether this is a genuine trend or merely a tendency to register unknown causes of death in this category. Seasonality and age distribution of these deaths are striking. The highest risk occurs during the third month of life, especially when this age is reached in winter; conversely, the generations who reach this age in summer are less affected. The consequence is a v...