BRITAIN has the worst child mortality rate in western Europe, according to new international figures.
The UK has 5.3 deaths per 1,000 live births and lags behind other high income countries, the research shows.
Although the rate is not rising, those behind the research said the level of neo-natal care in Britain needed examination.
However, American researchers said fewer children were dying globally, with deaths among the under-fives falling in almost every country.
The team at the University of Washington in Seattle said the number of deaths of children worldwide fell from 11.9 million in 1990 to 7.7 million this year.
A report in September by the United Nation's children's fund showed better malaria prevention and drugs to protect newborns of mothers with Aids had helped lower infant mortality from 12.5 million in 1990 to 8.8 million in 2008. But the new research suggests that 800,000 fewer young children died than Unicef estimates.
Writing in the Lancet medical journal, the researchers found that deaths fell in every region of the world, with increases in only Swaziland, Lesotho, Equatorial Guinea and Antigua and Barbuda. It has been suggested that Aids, smoking and obesity were reversing progress that had been made in helping people live longer, with adult mortality rates worsening over the past 20 years in 37 countries.
Along with the United States, New Zealand and South Korea, the UK's rate of child deaths has not fallen as quickly as expected. Globally the UK fell from 12th best in 1970 to 33rd best in 2010 on the issue.
The UK has reduced child mortality by three-quarters since 1970, and by almost half since 1990, but Austria, Belgium, Cyprus, Germany, Greece, Ireland, Israel, Italy, Luxembourg, Malta, Portugal and Spain have all overtaken the UK in the past four decades.
Study leader Dr Christopher Murray agreed the UK had seen a "big slide" in its ranking in terms of child mortality.
He said: "When you get to these low levels of child mortality seen in high-income countries, healthcare probably is an important component in the variation. Most of the deaths in places like the UK will be neonatal and you would have to look in more detail at what aspects of healthcare might explain that difference."
A Department of Health spokesman said infant mortality in the UK was at its lowest ever level. "However, the death of any child is one death too many and we must continue to do all we can to prevent those we can. This is why every child death is subject to a detailed review to understand why children die and what steps can be taken to protect others."
Dr Murray, director of the Institute for Health Metrics and Evaluation at the university, and colleagues assessed information from 187 countries from 1970 to 2009. They found child deaths dropped by about 2 per cent every year, lower than the 4.4 per cent needed to reach the UN's target of reducing child deaths by two-thirds by 2015.
Dr Murray said death rates were falling surprisingly fast in countries including Liberia and Niger, but that progress had stalled in rich countries like Britain and the US.
Where information was limited, researchers used modelling projections to estimate the number of deaths. The research was paid for by the Bill and Melinda Gates Foundation.