A leading charity has condemned what it calls the “shocking” postcode lottery that means young children in some parts of England are far more likely to be obese or have tooth decay than those in other areas.

The National Children’s Bureau (NCB) said that while variations are closely linked to poverty, poorer health outcomes in deprived areas are not inevitable.

Calling on ministers to make it their “national mission” to improve the health and development of under-fives, the NCB said local and national government must make similar efforts to those shown in narrowing gaps in educational achievement between rich and poor pupils.

Its report, Poor Beginnings, analysed data from Public Health England and other sources. This indicates a child in reception class in Barking and Dagenham, east London, is more than two-and-a-half times more likely to be obese than a child of the same age in Richmond upon Thames, 18 miles away in south-west London.

Similarly, a five-year-old in Leicester is more than five times as likely to have tooth decay than one in West Sussex, and a young child on the Isle of Wight is more than four times likely to be admitted to hospital with an injury than one in Westminster.

But some areas of poor deprivation buck the trend, suggesting more work needed to be done on how local strategies could make a difference, said the report. Children in Hartlepool, South Tyneside and Islington, north London, have relatively low levels of tooth decay despite high levels of deprivation. Similarly, Salford in Greater Manchester has low obesity rates, Walsall in the West Midlands has has low injury rates, and Waltham Forest and Haringey in London have good results across a range of outcomes.

Ironing out the differences could improve the early life chances of thousands of children, said the NCB. At a regional level, if under-fives in north-west England enjoyed the same health and development as those in the south-east, more than 15,000 cases of ill health could be prevented.

The report, which also looks at children’s overall development before starting school, comes just weeks before 152 local authorities in England take over responsibility for public health for under-fives from the NHS on 1 October.

This will happen shortly before 6.2% cuts – equivalent to £200m – begin in health grants to local authorities for this financial year. They were only ordered this summer and ministers say councils can include reductions in services for the under-fives, provided they meet legal obligations. This has raised fears health visitors could be among staff facing job losses.

The NCB said, however, that central government still has a pivotal role to play, not only in joining up approaches across Whitehall but also supporting local authorities and other agencies in working across boundaries. It said it must help build on the new devolutionary approach being planned in Greater Manchester.

Ministers should also look again at new baseline assessments for children starting school from 2016, said the NCB. These would only focus on literacy, maths and communication. “Without the continuation of a social and emotional development check at this age, it will be difficult to support the design and planning of local services and support for preschool children,” it said.

Anna Feuchtwang , the NCB’s chief executive, said: “It is shocking that two children growing up in neighbouring areas can expect such a wildly different quality of health.

“As these variations are closely linked to poverty, with those in areas with the highest levels of deprivation more likely to suffer from a range of health issues, we have to ask whether England is becoming a nation of two halves,” she said.

“The link between poverty and poor health is not inevitable. Work is urgently needed to understand how local health services can lessen the impact of living in a deprived area.”

Cheryll Adams, chief executive of the Institute of Health Visiting, said: “Health services must continue to be commissioned to recognise risk and intervene in the life cycle, in pregnancy and the very early years, and further investigate the variations uncovered in the report and how they relate to local health initiatives.”

Dr Carol Ewing, vice-president for health policy at the Royal College of Paediatrics and Child Health, said: “In a country which describes itself as having one of the best health systems in the world, this type of health inequality cannot and should not exist.

“There is an overwhelming body of evidence showing that prevention and early intervention works,” said Ewing. “We know that if children and families from the most vulnerable families are not supported in their early years, they are much more likely to suffer from ill health throughout their lives.”

The Department of Health said the government was committed to giving all children the best start in life. “For example, we have increased the number of midwives and health visitors, and later this year our childhood obesity strategy will outline how we will help children lead healthier lives,” it said in a statement.

“The variations found in this report underline the need for devolving public health spending to local areas who know the issues which affect their population.”