The actress joined the Weatherfield drama as Frankie Baldwin in 2004, but bowed out of the role at the end of 2006 to spend more time with her family.
Stephenson is now settled in London with her husband James Duffield and children Max and Zoe, who are now aged 7 and 2 respectively.
Reflecting on her decision to leave the show, Stephenson told The Mirror: "James and I decided that we wanted another child and I got pregnant. But my job was so full-on. Sometimes I was doing a six-day week when I had a big storyline and it was relentless.
"By the time I was heavily pregnant, I had that mad plot where Frankie developed feelings for her stepson Jamie (Rupert Hill) and I found it draining. It was a bit of a shame because I left the show in an exhausted state and I needed a couple of years off after that."
She added: "We never felt quite settled in Manchester either as we didn't know how long it would be. It felt right to leave and come back to London and devote some proper time to the kids."
Stephenson will be seen in a new impression show with Jon Culshaw on BBC One from Saturday.