Health authorities say they are considering removing out-of-hours emergency surgery and trauma services at either of two south Wales hospitals.
Prince Charles Hospital in Merthyr is being examined by health chiefs
Rhondda Cynon Taf Health Board is also looking at a merger on one site of consultant-led obstetrician delivery, neo-natal and paediatric services.
The board is examining the Royal Glamorgan and Prince Charles hospitals.
But it says it is not planning to remove 24-hour A&E care from either, one proposal previously considered.
Formal plans will not be published until "early summer", and will be followed by a period of public consultation.
The project manager of the redesign team said the current proposal was not final, and is subject to change and amendment.
A protest about the changes was held outside the Royal Glamorgan at Llantrisant last week.
In a statement, the board's redesign project team said: "There are no plans to close A&E departments at either the Royal Glamorgan Hospital or Prince Charles Hospital [in Merthyr Tydfil].
"Both the Royal Glamorgan Hospital and Prince Charles Hospital will continue to provide a vital role in the way in which healthcare services are organised and delivered in the future.
"Significant capital investment plans have already received assembly approval.
"This will enhance the current health facilities and support the proposed plans which aim to provide safe services as locally as possible."