The 43-year-old actress - who announced the birth of her and husband Keith Urban`s second daughter Faith Margaret, who was born via gestation carrier in December - says being a mother made her perform better in her latest Oscar-nominated role in `Rabbit Hole` and she would love to increase her family.
She said: "I want morechildren. I love being around that life force. People ask, `Was the film really hard?` Well, it wasn`t hard to find the emotions. It was hard to keep them in, to put them back. And I cannot imagine doing this if I didn`t have children."
The screen beauty - who has two adopted children, Isabella, 18, and 15-year-old Connor, with ex-husband Tom Cruise - insists something inside her was "altered" forever when she gave birth to her and Keith-s two-year-old daughter Sunday Rose.
She explained: "Something happens to you as a woman once you`ve given birth. You change on a cellular level. You change and are altered."
The star also admitted she would love to win the Best Actress Oscar at the upcoming Academy Awards because it would be a victory for the entire family.
She said: "When I won the Oscar for `The Hours` in 2003, it just went past. I would so love that moment with Keith because these sort of things are very much about your marriage.
"We talk about `Rabbit Hole` as `our` film because he gave up a lot for me to make it. It`s definitely our daughter Sunday`s film too."