The most recent paediatric consultant to leave Withybush hospital in Haverfordwest says staff are being 'sidelined' by the health board over changes to services.
Dr Gustavo Vas Falcao retired early at the end of last year after being frustrated that he couldn't change the service for the better.
Speaking to ITV Wales, Dr Vas Falcao said staff: "Are not being listened to. They're not being appreciated."
He added: "What frustrated me towards the end is that I couldn't change it [the service] for the better. I did try, but I couldn't."
Hywel Dda health board have previously said that the loss of staff "creates the risk of an unsafe, unreliable and fragile service” so the only option was to reduce hours.
The changes mean children have to travel to Carmarthen for care outside the new times.
Responding to the concerns raised by Dr Vas Falcao, Hywel Dda's chief executive Steve Moore said he recognised the concerns.
He said: "There have been issues in this organisation in the past and I think we are much better now at engaging with our staff. We've worked really hard to improve and clearly we've got more to do."
See more on this story on In Focus tonight on Wales at Six