An alarming gap between rich and poor is leaving the health and well-being of the UK's children in jeopardy, according to a major report by child health experts.
The Royal College of Paediatrics and Child Health (RCPCH) urges the Government to introduce a comprehensive national strategy and reverse cuts to public health as well as tighten controls over smoking, the sale of alcohol and advertising of foods high in fat, salt and sugar.
The RCPCH has created a snapshot of child health and well-being in the UK ranging from obesity and breastfeeding rates to asthma, diabetes, epilepsy and child deaths.
Professor Neena Modi, president of the RCPCH, said: "The health of infants, children and young people in the UK has improved considerably over the last 30 years.
"But it is tragic that the future health and happiness of a significant and growing number is in jeopardy because of an alarming gap between rich and poor.
"Children living in the most deprived areas are much more likely to be in poor health, be overweight or obese, suffer from asthma, have poorly managed diabetes, experience mental health problems, and die early.
"Poor health in infancy, childhood, and young adult life will ultimately mean poor adult health and this, in turn, will mean a blighted life and poor economic productivity.
"The UK is one of the richest countries in the world; we can and must do better, for the sake for each individual, and that of the nation as a whole."
The State of Child Health report says that one in five children in the UK is living in poverty, with those from the most deprived backgrounds experiencing much worse health compared with the most affluent.
The research found that in England, Scotland and Wales, more than one in five children in the first year of primary school were overweight or obese.
The report states that in 2015/2016, 40% of children in England's most deprived areas were overweight or obese, compared with 27% in the most affluent areas.
Among the measures demanded by the RCPCH is a ban on advertising for foods high in saturated fat, sugar, and salt in all broadcast media before 9pm.
It also called for improved support for breastfeeding and an expansion of programmes to measure the height and weight of youngsters.
The report also supports a minimum unit alcohol pricing policy similar to Scotland and extending the ban on smoking in public places and a ban on marketing of electronic cigarettes to young people.
Professor Russell Viner, RCPCH's health promotion officer, said it wanted UK governments to adopt a "child health in all policies approach", adding: "It has to be our ambition for the health of the UK's children to be amongst the best in the world; anything less and we are failing current and future generations."
Professor Viv Bennett, chief nurse at Public Health England (PHE), said: "Overall the health of children in England is improving. Infant mortality rates and child hospital admission rates are going down. We are also seeing fewer teenagers smoking or using harmful substances.
"But we agree that we have a major problem with childhood obesity and poor dental health, largely driven by sugar consumption.
"Wealth and population health are inextricably linked, which is why narrowing the health gaps between rich and poor communities underpins everything we do."
A spokesman for the Obesity Health Alliance, a coalition of over 35 leading charities, royal medical colleges and campaign groups, added: "We must take bold action now by bringing in measures like the Soft Drinks Industry Levy, reducing the sugar, saturated fat, and salt from everyday foods and restricting junk food marketing to children to give us a fighting chance to help make our children healthier now, and in the future."
A Department of Health spokesman said it was investing more than £16 billion in local government public health services over the next five years.
He added: "There is more to do but we have shown that we are willing to take tough action to protect public health and especially that of children - by banning smoking in cars if children are present, introducing a soft drinks industry levy and publishing a comprehensive childhood obesity strategy."