The incidence of the sudden infant death syndrome in relation to climate

Incidences of the sudden infant death syndrome (SIDS) for eight metropolitan communities in U.S.A. are shown to correlate strongly with the mean percentages of cold-wet weather experienced by these places in the seven months centred on January. For white infants aged 4–51 weeks at death, the incidence varies from about one per thousand live births in the more favourable climates to around two per thousand under the less favourable conditions of northwest U.S.A. Incidences are higher for the nonwhite infants but exhibit a similar variation with climate.To be able to extend the study to other countries for which cold-wet weather percentages are not available, a surrogate cold-wet weather index is developed, based on mean cold-season temperature, insolation and number of days with precipitation.Australian and British SIDS incidences related to the surrogate cold-wet weather index exhibit a variation parallel to that for U.S.A. but somewhat higher over the whole range.The incidences used in this study are from the more extensive investigations in which diagnosis was made as a result of thorough postmortem examination.