Persistent poverty affects one in five children in the UK, according to a new study.
While some children only experience poverty for part of their childhood, a fifth live with its effects until at least the age of 14, experts said.
A team of researchers, writing online in the Archives of Disease in Childhood, examined data for 10,652 children taking part in the Millennium Cohort Study.
All the children were born in the UK between September 2000 and January 2002 and were followed up through six survey waves, when they were aged nine months, three, five, seven, 11 and 14.
Poverty was defined as having less than 60% of average household income.
Of the total group, 62.4% of the children were never in poverty, 13.4% were in poverty in early childhood, 5% in late childhood and 19.4% were in poverty from birth until at least age 14.
Compared with children who never experienced poverty, those in persistent poverty were at three times greater risk of mental health problems, 1.5 times greater risk of obesity, and were almost twice as likely to suffer a long-standing illness.
The team, from the University of Liverpool and University College London Great Ormond Street Institute of Child Health, noted that in 2016/17, 30% (4.1 million) of all UK children were reported to be living in poverty, up from 27% in 2010/11.
By 2023/24, the figure is expected to hit 37%, affecting an extra 1.1 million children.
The team called for “a renewed commitment” by the UK Government to prioritise ending child poverty.
They said health professionals “are well placed to argue that policies and services in the UK should fulfil our moral and legal responsibility to ensure that every child is able to achieve their full potential”.
Professor Russell Viner, president of the Royal College of Paediatrics and Child Health, said: “The impact of poverty on children can be devastating – not only to their physical health in terms of increased risk of malnutrition, respiratory problems from poor housing and infection – but also their mental health.
“This latest research serves to highlight the importance of tackling poverty if the relatively poor outcomes for child health in the UK are to improve.
“That means measures such as binding national targets to reduce child poverty backed by a national child poverty strategy, the reversal of cuts to universal credit and the reversal of public health cuts.”
A Government spokeswoman said: “As the authors say, this report doesn’t establish a causal link between poverty and poor health.
“UK households with children have a lower persistent poverty rate than the EU average including a rate lower than both France and Germany.
“We want every child to have the best start in life, which is why our long term plan for the NHS, backed by an extra £33.9 billion a year by 2023/24, puts prevention at its heart.
“We’re also spending £95 billion a year on working-age benefits and provide free school meals to more than one million of the country’s most disadvantaged children.”