World trends in infant mortality since 1950.

Despite the considerable progress made in recent decades, and perhaps even partly because of the very uneven distribution of this progress, infant mortality is still very high in some regions, whereas in other regions it is tending, if not disappear completely, at least to become numerically negligible even though remaining a matter of social concern. Whereas in tropical Africa almost one child in five dies before its first birthday, in Japan or Scandinavia it is one child in a hundred. Infant mortality rate varies between these two extremes, but there is a substantial gulf between the "most developed" regions which are all below 30% and the "least developed" regions which fall into three categories: 65-100% (Latin America, Eastern Asia except Japan), around 140% (Northern Africa, South Asia, Melanesia), and about 200% (topical Africa). These inequalities between countries overlap with inequalities between social groupings by urbanization, social/occupational level, education and income, are all variables that are correlated with infant mortality to a greater or lesser degree. The pace of the progress achieved since 1950 seems to be independent of the starting level. Contrary to the development of mortality at other ages, it is not in the countries with high mortality that infant mortality has decreased most. The pace of reduction divides the most developed regions into three distinct groups: very rapid reduction (Japan), rapid reduction (Scandinavia, Western Europe, Southern Europe and Eastern Europe), and slower reduction (British Isles, Northern America and Australia/New Zealand). Thus Japan rapidly caught up with Western Europe and the English-speaking countries and has now reached the same level as Scandinavia. On the other hand, the English-speaking countries have fallen behind the Scandinavian countries and are now at par with Western Europe. The reduction of infant mortality mainly concerned deaths of children over one month of age or even over one week of age and otherwise is due to reduction of infectious diseases. Consequently, in the most developed regions mortality is highly concentrated in the first week of life and is mainly attributable to the "causes of perinatal mortality" and the "congenital" anomalies". In the least developed regions, on the other hand, the infectious or parasitic diseases are still of decisive importance and the risk of death remains very high throughout the first year of life and even beyond. The risk may be even higher during the second year, when weaning takes place abruptly and results in serious difficulties in feeding.