Although we think Keith Urban had a little something to do with it, his wife Nicole Kidman believes swimming in the waterfalls of the Australian Outback contributed to her pregnancy.

The 41-year-old actress, who gave birth to daughter Sunday Rose in July, says that she and six other women who swam in the waters of a small Outback town during production of her upcoming film 'Australia' all had babies, the majority of whom were girls.

"I never thought that I would get pregnant and give birth to a child, but it happened on this movie," Kidman told Australian Women's Weekly magazine. "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 (who also directed Kidman in 2002's 'Moulin Rouge'), was filmed in Kununurra, a small town in far northern Western Australia state. In the film, set for release in November, Kidman plays a noblewoman on a cattle drive in Australia during World War II.

Kidman, who has two teenage children with ex-husband Tom Cruise, said, "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!"