The 43-year-old actress welcomed Sunday Rose with husband Keith Urban in 2008.
Appearing on The View, she said, 'Four years ago I read a review of the play and it was a beautiful review. We approached the playwright and he let us option the play and that was before I was pregnant.
'And then I got pregnant, because it takes a long time to make films, particularly ones like this, and I went, 'I can't go anywhere near this.' Hormonally and everything else I was like, absolutely not.'
But after such a struggle to get the film off the ground, she said she knew that she would have to follow it through.
She added, 'Then the financing became available and it was a confluence of events and everything came together and I went, 'Do I run away or do I stay?' Now we'll see how committed I am, and I said, 'I have to make it.''