Three-year-old Elizabeth Gregory was one of the tiniest babies ever to have survived at the NICU unit at Bath's Royal United Hospital.
Her mum Karen, of Penleigh Close, Corsham, was told by doctors if her daughter had been born three days earlier they would not have been able to save her.
Elizabeth, weighed just 1lb 6oz when she was born nearly four months early on March 8, 2004.
Mrs Gregory, 36, and husband Dave, 38, are backing the Forever Friends Space to Grow campaign, which needs to raise £4.5 million for a new improved NICU ward.
Mrs Gregory, who is a registered childminder, has praised the staff at the neo-natal unit for their constant care and support.
She said: "It was a traumatic time and the first few weeks were by far the worst but the whole way through it the staff were amazing.
"Dave spent all night staying with the nurses talking about the equipment. They've got so much to give."
She hopes that a larger unit will help parents cope more easily with the trauma of having a sick child.
She said: "You have to drive through Bath, scrabble for a parking space and you walk in and there's three other families in your way.
"The funny thing is before we had Elizabeth we didn't give special care a thought. It wasn't until our lives were thrown into that world that we saw this little unit do such fantastic work."
Like many other parents who are supporting the campaign, Mrs Gregory noticed the unit's lack of privacy more than anything else.
"If you wanted a moment to be upset there was no where to go because there were two or three people in each room with you. It's just not very nice really.
"You were always tripping over each other, it was very noticeable."
Although the conditions in the ward were stressful, Mrs Gregory and her husband formed long-standing friendships with other parents and nurses.
"We couldn't wait to get there in the mornings and see this group of friends we had made. The staff there made it special in a funny way. When we get together we reminisce about things and everyone has fond memories - even though it was traumatic."
Elizabeth, who has an older brother, Alister, 11, and a sister, Katie, nine, is now like any other three-year-old and has no long-standing health problems after her traumatic start to life.
Her mother said: "There's definitely something in her character, she has more spirit, she doesn't want to miss a thing."
So far £600,000 has been raised in just four weeks.
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