The 41-year-old Aussie, who gave birth to daughter Sunday Rose in July, said she and six other women who swam in the waters of a small Outback town during production of the epic romance "Australia" became pregnant.
"I never thought that I would get pregnant and give birth to a child, but it happened on this movie," Kidman told The Australian Women's Weekly in an exclusive interview for the magazine's 75th anniversary edition, released Wednesday.
"Seven babies were conceived out of this film and only one was a boy. There is something up there in the Kununurra water because we all went swimming in the waterfalls, so we can call it the fertility waters now."
"Australia," directed by Baz Luhrmann, was filmed in Kununurra, a small town in far northern Western Australia state. The film, which follows the story of a noblewoman on a cattle drive in Australia during World War II, is due for release in November.
The actress also commented on the relatively diminutive size of her baby bump throughout her pregnancy.
"I'm so lucky I'm so tall, so I carried small and also, I have to say, I had a birth that I was blessed with, a labor that was very good and a baby that was very good to me in that regard," said Kidman, who is married to country music crooner Keith Urban and has two adopted children with ex-husband Tom Cruise.
"To be given this again is a beautiful thing. To have raised Bella and Connor since I was 25 and now to be able to do it again at 41 ... wow!"