"The slowdown is of particular concern in the case of Africa and south-east Asia because it is occurring at relatively high levels of mortality and in countries with severe economic dislocations," the researchers write. "As the HIV/AIDS epidemic continues to unfold in Africa and parts of Asia, further reductions in child mortality will become increasingly unlikely until substantial progress in controlling the spread of HIV is achieved."

The study traces the dramatic fall of almost 60 per cent in child mortality during the second half of the 20^th century. It shows that about 10.5 million children under five died last year, 2.2 million less than in 1990. Of these 10.5 million deaths, 3.8 million occurred in Africa, with a further 2.5 million in India and 750,000 in China.

The fall in child mortality means a reduction in the likelihood of a baby dying before its fifth birthday. Today, the probability of a newborn baby dying before the age of five is, globally, about 7%, compared with 10% in 1990, 12% in 1980 and 25% in 1950.

The drop in child mortality also brings the world’s average rate down to an estimated 67 deaths per 1,000 live births. At the World Summit for Children in New York in 1990, leaders of more than 150 countries set a target of 70 deaths per 1,000 live births that all countries of the world were to reach by the year 2000. At that time the global rate averaged about 85 per 1000 live births, already a striking drop from the 180 deaths per 1,000 live births in 1950.

At least 57 countries have not reached the 70 per 1,000 target, the Bulletin article points out. Some countries have child mortality rates estimated to be above 200 per 1,000 live births. They include, in order of descending rates, Niger (335), Sierra Leone (312), Afghanistan (264), Malawi (219), Guinea and Liberia (205), Guinea-Bissau (202) and Somalia (201). Seven of these eight countries are in WHO’s African region, which has an average rate of about 150, vs. 88 for South-East Asia, 67 for the Eastern Mediterranean, 46 for the Western Pacific, 34 for the Americas and 18 for Europe.

What’s more, the pace of the decline in child mortality is slowing. Seven countries, all in Africa, have seen little or no change in their child mortality rates over the past 50 years. They are Burundi, Lesotho, Madagascar, Mauritania, Nigeria, Sierra Leone and Tanzania.

A further seven countries have even experienced increases in child mortality: five in Africa-Botswana, Namibia, Niger, Zambia and Zimbabwe; one in South-East Asia - Democratic People’s Republic of Korea; and one in the Western Pacific - Papua New Guinea.

Africa as a whole recorded the most sluggish decline in child mortality among the six WHO regions—42%, compared with 60-72% for other regions. And in Africa, about 15% of newborns are likely to die before reaching age five, compared to under 2% in Europe.

The reasons for the slump are unclear but in some countries, economic problems, civil strife and a poor choice of interventions used to try to reduce deaths among children are among the underlying factors. The authors of the study warn that the full impact of the HIV/AIDS epidemic on child death rates has not yet been felt. They say the disease has the potential to slow down dramatically, if not reverse, gains in childhood survival in some African and Asian countries.

"It is important," they add, "to recognize that reversals in public health are possible and can substantially alter long-term declines in mortality. Two examples are the dramatic increase in adult mortality in Russia and several other eastern European countries in the late 1980s-early 1990s, and the emergence of HIV/AIDS as a leading cause of adult death (and the leading cause in Africa)."

The authors of the study are Omar Ahmad, Alan Lopez and Mie Inoue, of the Burden of Disease Unit of WHO’s Global Programme on Evidence for Health Policy.

In an attempt to find out which factors might be responsible for the declining child mortality rates that have been observed in most countries over the past 50 years, Rutstein (pages 1256–1270) studied data from 89 health surveys conducted in 56 developing countries. The factors most strongly linked to declining child mortality were better nutritional status and environmental conditions (better water supply, sanitation and housing). Next came greater availability of medical care during pregnancy, at birth and for children with diarrhoea, followed by the availability of electricity and education of mothers.

Growth retardation, or stunting, is a direct consequence of poor feeding and is associated with increased child mortality. A new study by de Onis et al. (pages 1222–1233) found that stunting in developing countries has dropped in prevalence from 47% in 1980 to 33% today and if these trends continue will fall to about 29% by 2005. That means that there are some 182 million stunted children in developing countries today, or 40 million fewer than two decades ago. Of the 182 million, 70% live in Asia, 26% in Africa and 4% in Latin America and the Caribbean. A downward trend is seen for all Regions, although Africa shows the smallest decline, down from 41% to only 35%. In Eastern Africa, stunting has been on an upcurve since 1980 and today affects 48% of pre-school children, or 22 million, vs. 12.9 million 20 years ago.

Better nutrition is not the only reason for the fall in child mortality over recent decades. Another, according to data presented by Victora et al. (pages 1246–1255), could be the increasingly widespread use of oral rehydration therapy (ORT) to manage diarrhoeal disease. Over the past decade, the estimated number of under-five-year-olds dying from diarrhoea fell precipitously—from 3.3 million to 1.5 million, a saving of 1.8 million young lives, while deaths from all causes in this age-group fell by 2.2 million. Over the same period, the proportion of diarrhoea episodes managed with ORT in developing countries soared, from 40% to 69%.