Worried families fear "it's the beginning of the end" for children's healthcare services in Ceredigion after plans to cut the number of beds on a children's ward.
They said being transferred from the Angharad Ward in Aberystwyth's Bronglais Hospital to Glangwili in Carmarthen would have a financial and emotional impact on them.
Judy Morgan, who has teamed up with other families to protest the closure, said: "I can't even imagine driving for an hour with a poorly child."
Hywel Dda health board said staff "understand some parents will be concerned" about the changes over the next six months, but they would continue to "offer the very best care".
The shared "trauma" of having very poorly children brought mothers Ms Morgan and Cerys Humphreys together.
When they learnt that capacity at Angharad Ward would be temporarily reduced, they decided they had to do something for the hospital that has done so much for their own children.
As a specialist maternity photographer, Ms Morgan decided to ask local families to share snaps of their little ones as well as a summary of their time on the ward.
"I thought the best way to get through to people is the visual way," she said, after using more than 50 images of young patients to make a protest collage.
"There was lots of stories. There were children who needed open access to the ward because they're going through things like chemotherapy, which is obviously devastating.
"One of the stories was just really, really sad - a child needed a brain surgery, and if it wasn't for Angharad Ward, they don't know what would happen."
While care will still be available on the ward according to Hywel Dda health board, very sick children will be transferred to Glangwili in Carmarthen.
Ms Morgan said families from further afield, from areas such as Tywyn, have contributed to the protest collage, sharing their concerns that alternative hospitals such as Bangor and Carmarthen are hours away.
"I can't even imagine driving for an hour with a poorly child," she said.
When her own children required care in Carmarthen, Ms Morgan said splitting her time between her home in Aberystwyth and the hospital "had a massive impact" on her mental health.
"It was really difficult to go through all of those emotions, all of those thoughts, while being away from home."
According to a report presented to the health board, the ward had been "operating at risk" since the beginning of 2024 because of "shortfalls in the availability of paediatric nurses".
The changes to capacity will last up to six months, according to the health board.
But for the families who use Ysbyty Bronglais, the fear is the ward will eventually close completely.
"It would just be absolutely devastating," said Ms Humphreys from Aberystwyth, whose 16-month old daughter, Nel, has been treated in Cardiff, Bristol and Carmarthen.
She said travelling away from home to get her baby the care she needed was "financially crippling" for her family.
Ms Humphreys added that the geographical convenience of Ward Angharad, coupled with the fact that the staff there know her daughter's needs well, is "invaluable" and "reassuring".
"It's just the beginning of the end if we let this happen," said Ms Humphreys, who added she fears diminishing children's services will deter people from moving to the area.
Colin Harding's son, Welan, spent weeks on the Angharad Ward as a result of complications with his appendix.
Mr Harding said he and his wife, Gwerfyl, were at Welan's side "day and night" whilst also running their businesses and home in Machynlleth more than 20 miles (32.1km) away.
After Welan made a full recovery, the family organised a charity bike ride from Wolverhampton to Aberdyfi, raising £10,000 for the children's ward at Bronglais Hospital.
"I feel angry to be honest at what's happening now after all of the money was raised," said Mr Harding.
Lisa Humphrey, general manager of women and children's services at Hywel Dda health board, said "the majority of those who attend will continue to be cared for at Bronglais Hospital for up to 24 hours".
She added that small numbers will be transferred to Glangwili Hospital in Carmarthen.
"We appreciate that this will be difficult for some families who live further away, but our modelling shows that these numbers are likely to be small and we will offer the very best care and support to families during their time with us."