Nadine Coyle says launching a Girls Aloud reunion would be like "moving a mountain".
The girl band, which shot to fame in 2002 on TV talent show Popstars: The Rivals, went on hiatus on 2009 before splitting in 2013.
Derry native Nadine (34) told Hello! magazine: "People are always asking if we'll do something for our 20-year anniversary. It would be nice, but it takes so much, it's like moving a mountain. So many people are involved."
She said reviving the band with Cheryl, Sarah Harding, Nicola Roberts and Kimberley Walsh "would take a lot of planning and organising".
The singer said her confidence drained away during her time in the chart-topping five-piece.
"I was losing sight of myself and started to get anxiety and stress," she said.
"You work at such a pace you don't have time to sit with yourself."
Nadine had daughter Anaiya with American football star Jason Bell in 2014 and they later split after an 11-year relationship.
"There are no issues, no stress," the star told Hello! "We're not together as a couple, but I see him every day. We get on great."
With the release of her latest single, All That I Know, due on January 31 Nadine has said that although the lyrics are about longing for a former partner, the song was not inspired by Jason. Fans have been told to expect a "new era" in her music as she plans to reveal more in her lyrics.
Nadine returned to the limelight in the autumn when she headed to the Australian jungle for an appearance on ITV reality show I'm A Celebrity... Get Me Out Of Here!