Carrie Underwood found it ''physically impossible'' to sing after she had stitches in her face.

The 35-year-old singer took a tumble outside her home last November, which left her with a broken wrist and 40 stitches to repair cuts on her face, and she admitted the treatment made it difficult to record vocals for her album 'Cry Pretty'.

She told Vulture: ''I felt like the differences were more in my head than they were in anybody else's that would listen to the things I was doing. I had wanted to be in the studio sooner than I was, actually recording these songs, but I had stitches inside my mouth, outside my mouth. It was physically impossible.''

But the 'Before He Cheats' hitmaker - who is expecting her second child with husband Mike Fisher, the father of her three-year-old son Isaiah - admitted her producer, David Garcia, couldn't hear the problems with her voice that she was worried about.

She said: ''Going into the studio for the first time, it was a mind game: 'Do I sound the same? Is my diction the same? Does my mouth move the same as it did before?

''I would sing something and then look at David and be like, 'Did that all come out clearly?' My m's and b's and p's were kind of the issue. And he was like, 'I thought it sounded great.' ''

Carrie has now come to accept that her accident may have had an impact on her vocals and knows her voice will change with time anyway.

She said: ''Things change just as you get older; muscles change. I kind of expect I'm not always going to sound like I'm 22 coming off of 'American Idol'. Hopefully, I get better.''