The 26-year-old actress - who has a 10-month-old son Winston with husband Laurence Fox - thinks she is too young and immature to have a child.
And she worries she'll fill his head with rubbish. She said: "You think having a child will kind of centre you as a person because you're a parent and therefore you're supposed to be a grown-up.
"But, if anything, I think about the fact that I'm not grown up enough.
"The fear sets in when passing your knowledge on to your child
"You realise you don't want to fill his head with a load of rubbish. I need to really think about what I believe in before I tell him anything. There's a lot of soul-searching."
