Death rates 'higher' among young adults than children
Premature deaths are now more likely to occur in adolescence and early adulthood than in childhood, a new global report claims.
The study in The Lancet looked at data from 50 countries - rich, middle-income and poor - over 50 years.
It found that while mortality had fallen overall, rates were now relatively higher in teenagers and young adults, than in young children.
Violence, suicide and road accidents are being blamed.
The new study shows death rates among young people have fallen dramatically over the last 50 years across the globe.
Mortality in children aged one to nine has fallen by between 80% and 93%, thanks largely to fewer deaths from infectious disease.
Death rates have not been dropping as fast among teenagers and young adults.
In young men aged 15-24, mortality has dropped between 41% and 48%, again largely because of success in combating disease.
But 'injury', be it violence, suicide or road accidents, has emerged as the biggest killer of young men in all regions, and the biggest killer of young women in rich and eastern European countries.
Violent deaths are on the rise in both young men and women in real terms.
This means that although mortality has fallen overall, it is now higher among teenagers and young adults than in children.
Young men aged 15-24 are now two to three times more likely to die prematurely than young boys aged one to four, the researchers claim.
"Modern life is much more toxic for teenagers and young people," says Dr Russell Viner of University College London, who led the study. "We've had rises in road traffic accidents, rises in violence, rises in suicide which we don't see in young children.
"The teenage years were the healthiest time of our life. It's no longer true."
This might not be the complete picture. The study doesn't take into account the poorest countries from sub-Saharan Africa, because the data was not available, say the researchers.
There are also regional variations. There was a peak in suicide rates observed during the post-communist countries in the late 1990s, for instance, while suicide rates have started to fall in rich countries in recent years.
But Dr Viner says trends first seen in the West are now being seen in developing countries, as the move to cities brings benefits and risks to the urban young.
"It seems that economic development, the move to cities, increasing urbanisation and social dislocation are actually quite toxic for our young people in terms of mortality," he says.
Co-author Dr Michael Resnick, of the University of Minnesota, told the BBC: "What is clear is that the greatest threats to young peoples' health, outside of living in extreme poverty and in 'hot zones' of infectious disease and war, stem from the behaviours in which young people engage, and the contexts in which they find themselves."
He said governments had to focus "on violent neighbourhoods, extreme impoverishment and lack of access to fundamental resources and services, and the hopelessness that comes from utter lack of prospects and opportunity".