Kidman, now married to Keith Urban, is also a mother to two young daughters Sunday Rose, 4, and Faith Margaret, who is nearly two.
She tells the magazine that announcing she was pregnant in 2008 was one of the greatest surprises of her life.
"I had so much time thinking that wasn't going to happen in my life and trying to understand that. When it did happen - and for it to be a surprise - that was great. I had tried and failed and failed and failed. Not to be too detailed, but I've had an ectopic pregnancy, miscarriages and I've had fertility treatments. I've done all the stuff you can possibly do to try get pregnant.
"Every woman who has been through all those ups and downs knows the depression that comes with it. So the way it just happened with Sunday was like, what? The percentages were so low. It is the miracle in my life."
The other miracle in her life she says was meeting Urban.
"We really, really love each other. We really like each other and respect each other, too. I never, ever take him or our love for granted and I always keep in my mind that my dream is to grow very old with him."
- AAP