Millions of infants in developing countries are being put at risk because they are not being breastfed properly, a study suggests.
Breast milk boosts babies' immune systems
Researchers at the World Health Organisation (WHO) analysed survey results from 94 developing countries.
They found just 39% of infants were exclusively breastfed for the first six months, as recommended.
Writing in BMC Medicine, they said women were also failing to breastfeed infants up to the age of two.
The WHO passed a resolution three years ago calling for all infants under six months to be fed exclusively on breast milk.
This was largely in response to growing evidence that breast milk has major health benefits.
It boosts infants' immune system and protects them against a range of serious diseases, such as pneumonia and diarrhoea.
This is particularly important for children in developing countries.
But there is also growing evidence that, in the absence of safe alternatives, exclusive breastfeeding may reduce the risks of women with HIV passing the disease onto their newborn babies.
However, this latest study suggests the message is not getting through to women in developing countries.
For instance, in Africa just one in four women exclusively breastfed their infants for the first six months.
The researchers also examined whether women were following advice to continue to breastfeed their children until they were two years old.
They found that most young children are breastfed until they are two. Overall, just 14% of those between six and 11 months and 32% of those between 12 and 23 months are not breastfed.
However, there were variations. In South America and the Caribbean only 37% of children over the age of one were being given some breast milk.
The researchers said the overall figures could be even worse since the surveys may have overestimated the number of children being breastfed.
They said more needs to be done to encourage more women to breastfeed in line with the recommendations.
"The size of the gap between breastfeeding practice and recommendations is striking.
"More attention should be given to increasing breastfeeding, especially exclusive breastfeeding, and to monitor breastfeeding trends."
Professor Andrew Tomkins, head of the Centre of International Child Health in London, welcomed the figures.
"The figures are moving in the right direction," he told BBC News Online.
Professor Tomkins said encouraging women to breastfeed their children sometimes involves challenging traditions or cultural norms.
"Women need a lot of support and confidence building. It is sometimes easier said than done.
"But studies have shown that it can be done. It is certainly worth doing. Breastfeeding protects the child against infection."