Keira Knightley says motherhood puts "everything into perspective".

She explained: "I think motherhood puts everything into perspective, I really do. I've been offered [the Thérèse Raquin part] a bunch of times and I've always gone, 'Well, this is scary and this is really difficult'.

"I still find it terrifying, but why not give it a go. I'm very grateful to become a mother while doing something this unbelievably difficult, because honestly the worst that could happen is that you fail."

The 30-year-old actress is also pleased she has had the "opportunity" to balance her career and personal life, bringing up Edie and starring in the stage show.

She told the Daily Telegraph newspaper: "You try your best and I've been really lucky that I have had the opportunity to be working and finding interesting things, and working with interesting people while being a mum at the same time. Ultimately as long as my kid is alright, everything is fine."