Seasonality in Recent Mortality in Japan, UK and USA

Abstract

With the turn of the 1970's, the seasonal variation of Japanese mortality, early infant mortality in particular, has undergone conspicuous changes as reported previously. The present report presents what changes the UK and the USA also have shown in total mortality in comparison with Japan, and what might well be responsible for the different changes in recent deaths in the three advanced countries. In total mortality, the UK shows predominant concentration in the cold months, while the USA has come to show such moderateness as to be called desceasonality i. e. a seasonal variation pattern nearly equal to a straight line. Japan herself stands in an intermediate position with a high peak in winter and a small hill in summer. In cerebrovscular mortality, deaths are considerably concentrated in winter in Japan and the UK but conspicuously moderate as a whole in the USA. In infant mortality, signs of deseasonality are increasing in the USA and Japan, but there are noteworthy differences between the two nations : a bimodal curve is seen in Japan whereas ups in JanuaryFebruary and in April-June and a trough from July to September are witnessed in the USA seasonal variation pattern. The marked lowering and the increasing deseasonality of mortality in recent years in Japan are ascribed in the final analysis to the high-rate industrial growth and the subsequent urbanization of Japanese society with better living conditions and improved medical services. As for the UK, sanitary conditions had surprisingly improved as early as the middle of the nineteenth century and the representative seasonal variation pattern came to the fore earliest in the world and remained stabilized for a long span of time, and in the 1970's, no marked changes came to appear as compared with the increasing deseasonality in the USA and the mounting signs of deseasonality in Japan hitherto regarded as 25-30 years behind the USA. The USA is a vast country including high latitudes and subtropical areas and calls for regional analysis in the southern states generally less advanced than other industrial areas, deaths, infant mortality in particular, are surprisingly concentrated in the cold months in contrast to the general deseasonal pattern in many northern states and remain quite unchanged in the 1960's and 1970's. An international comparison of the seasonal disease calendars finally reveals that Japan in the 1970's shows noteworthy changes compared with the 1930's and 1950's, while no such noticeable changes are seen in the UK and the USA.