Insufficient progress has been made in most developing countries to meet the United Nations' target of halving the proportion of children who suffer from hunger by 2015 compared with 1990 levels, according to a systematic analysis of data on children's height and weight, published in Lancet. Although the nutritional status of children under five has improved overall since 1985, one in five infants and children in developing countries is still moderately or severely underweight, amounting to an estimated 110 million children worldwide. Another 148 million are mildly underweight.

The UN set the target as part of its Millennium Development Goals. This new analysis, led by Professor Majid Ezzati from the School of Public Health at Imperial College London, estimates that while 61 out of the 141 developing countries studied are likely to meet this target, the developing world as a whole has less than a 5% chance of succeeding. Progress has been uneven between regions, with Asia and Latin America making the strongest improvements and sub-Saharan Africa falling behind.

Because nutrition has a strong effect on children's growth, nutritional status in children can be assessed using scores based on their height and weight relative to their age, called height-for-age and weight-for-age Z scores (HAZ and WAZ).

Researchers from Imperial College London, the World Health Organisation and universities in the US compiled HAZ and WAZ data from national surveys and other sources, and used statistical methods to estimate average Z scores and the prevalence of undernutrition (defined as insufficient food intake and absorption) for entire countries.

The results show that:

+ The proportion of children classed as moderately to severely underweight fell from 30.1% to 19.4% between 1985 and 2011 in the countries studied. The prevalence of moderate to severe stunting (insufficient growth in height for their age) declined from 47.2% to 29.9%.

+ South Asia, the region with the worst nutritional status in 1985, has improved considerably, but undernutrition is still a major issue. About one half of the world's underweight children live in South Asia, mostly in India.

+ Undernutrition worsened in sub-Saharan Africa from 1985 until the late 1990s, when height and weight scores began to improve. The deterioration may have been due to economic shocks, structural adjustment, and trade policy reforms in the region in the 1980s and 1990s.

+ In Ivory Coast and Niger, nutritional status was measurably worse in 2011 than it had been in 1985.

+ Height and weight scores improved in all other regions, with the largest improvements in South Asia, East and Southeast Asia, and Southern and Tropical Latin America. The biggest improvement in children's height occurred in China and Vietnam.

+ Some countries in Latin America, such as Chile, now have almost no undernutrition. The proportion of underweight children almost halved per decade in Brazil.

+ As of 2011, about half of children in Burundi, Yemen, Timor-Leste, Niger and Afghanistan are moderately or severely stunted. More than one third of children in Timor-Leste, Bangladesh, Niger, India and Nepal are moderately or severely underweight.

This new study includes estimates of all levels of malnutrition, unlike previous analyses, which excluded children who were mildly malnourished. The statistics suggest that in most countries, the improvements are due to population-wide improvements in nutrition, rather than interventions targeting high-risk children.

Professor Majid Ezzati said: "Our analysis shows that the developing world as a whole has made considerable progress towards reducing child malnutrition, but there are still far too many children who don't receive sufficient nutritious foods or who lose nutrients due to repeated sickness. Severe challenges lie ahead.

"There is evidence that child nutrition is best improved through equitable economic growth, investment in policies that help smallholder farmers and increase agricultural productivity, and primary care and food programmes targeted at the poor. We mustn't allow the global economic crisis and rising food prices to cause inequalities to increase, or cut back on investments in nutrition and healthcare."