Plans have been put forward to cut hospital services in two-thirds of England, a BBC analysis shows.
The proposals have been put forward by local NHS bosses as part of a national programme to transform the Health service and save money.
They include everything from full closures of hospitals to cutting some specialist services such as accident and emergency and stroke care.
Ministers argue patients will receive better care in the community.
But a review of the plans by the King's Fund think tank warned they were not always credible because there were not enough services outside of hospitals.
It warned GPs, district nursing and council care services were already "feeling the strain" and could not currently cope with an increase in workload.
And the King's Fund said further reductions in the number of hospital beds could de-stabilise services that were already "stretched to their limits" following the difficult winter.
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In total, 44 local plans have been drawn up across England.
The BBC has analysed each one and has indentified 28 that mention some form of cut to local hospitals.
- Plans to reduce the number of hospital sites in Leicester, Leicestershire and Rutland from three to two
- Maternity and children's services being "centralised" on to one site in Lincolnshire
- A warning in West Yorkshire and Harrogate that having five hyper-acute stroke service may "no longer be viable"
- The downgrading of two out of three A&Es in Mid and South Essex, with only one retaining specialist emergency care
- In South West London, proposals to reduce the number of major hospitals from five to four
- Plans in Nottinghamshire to significantly downsize City Hospital and reduce the number of beds across Nottingham by 200
- In Cambridgeshire and Peterborough, consideration being given to centralising specialised orthopaedic trauma services at two local hospitals
The plans - known as sustainability and transformation plans - have been drawn up as part of NHS England's five-year strategy to release £22bn of efficiency savings by 2020.
Reviews were set up in early 2016 and consultations on major changes will take place later this year with the hope implementation will follow soon after.
But the King's Fund warned the changes could be subject to legal challenges.
However, Prof Chris Ham, the think tank's chief executive, said they were still the "best hope of delivering essential reforms" in the NHS, as care needed to be moved out of hospital.
This is seen as vital because the ageing population and growth in long-term conditions such as dementia and heart disease mean people are more likely to benefit from support in the community to stay well rather than inpatient hospital care when their health deteriorates.
But Prof Ham said this could not be done without extra funding - and urged the government to find the money to invest in the services to enable transformation to happen.
A £1.8bn pot set aside this year for funding transformation had already been swallowed up by deficits, figures released on Monday showed.
"Local plans must be considered on their merits, but where a convincing case for change has been made, ministers and local politicians should back NHS leaders," Prof Ham said.
A Department of Health spokesman said extra money was being invested in the NHS this Parliament.
"These NHS plans - developed by local doctors, hospitals and councils working together with the communities they serve - will help patients get better care," he added.
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6. Coast, Humber and Vale
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11. Shropshire and Telford and Wrekin
15. Leicester, Leicestershire and Rutland
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18. Coventry and Warwickshire
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21. Cambridgeshire and Peterborough
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