Nearly 23 million people in England - more than 40% of the population - could be affected by proposed cuts to A&E departments, doctors are warning.
The analysis of NHS plans by the British Medical Association also warned the changes were being rushed through without the evidence they will work.
The proposals have been put forward by local managers seeking to make savings under the direction of NHS England.
Bosses have argued services in the community will be boosted in return.
Under the so-called "sustainability and transformation programme" (STP), England has been divided into 44 areas and each asked to come up with its own proposals.
After analysing local plans, the BMA found:
18 of them, covering a population of 22.9 million, involved the closing or downgrading of an A&E department
14 of them, responsible for 17.6 million patients, propose closing or merging a hospital
13 of them, covering a population of 14.7 million, have put forward closing hospital beds