The actress will return to the ITV1 soap as Michelle Connor in the autumn. Marsh, who has been on maternity leave, will make her comeback alongside co-star Keith Duffy (Ciaran McCarthy).
However, Duffy has confirmed that he won't be returning to the Manchester serial for long, leaving fans to speculate on what will become of Michelle and Ciaran's relationship.
Commenting on her co-star's decision, Marsh told New magazine: "He needs to be at home in Dublin to support his daughter Mia - who has autism - when she makes the transition to secondary school.
"I'm not sure what that means for Michelle and Ciaran's relationship because I haven't seen any storylines, but if they do break up it will be interesting to see if he breaks her heart or she breaks his."
Coronation Street producer Phil Collinson recently told Digital Spy that the couple will plan to make a "flying visit" to the Street, but the "story" will see their plans change.
He said: "Michelle will go back into the factory and will be quite instrumental in helping Carla to run Underworld again, so that's where Michelle's heading back to."
Meanwhile, Marsh also confessed that she would like a waxwork like co-stars William Roache and Anne Kirkbride.
"I'd definitely have one done if I was asked because it's such an honour," she said. "But I'm not sure anyone would want one unless it was to stick a wick in the top!"
Read the full story in this week's New magazine - out today.
> Kym Marsh hits back at 'Coronation Street' crisis claims
> Keith Duffy discusses Corrie return