"The couple are thrilled," Catherine Olim says in a statement.
For Kidman, 40, this will be her third child. She and her former husband, Tom Cruise adopted two children during their marriage: Isabella, now 15, and Connor, 12.
As for where Kidman and Urban, 40, who will be a first-time parent, may bring up their impending arrival, the couple, though both from Down Under, purchased a farm near Leipers Fork, Tenn., a half-hour southwest of Nashville, in 2007.
The couple, who have been married 18 months, wed, after a yearlong courtship, on June 25, 2006, in a candlelit ceremony at Sydney, Australia's Cardinal Cerretti Memorial Chapel on St. Patrick's Estate at Manly. Guests at the black-tie event included Russell Crowe, Hugh Jackman, Naomi Watts and Rupert Murdoch.
Before the couple even started dating, Kidman made her desire for more children clear. In April 2005, she told reporters that her biological clock was ticking. "I have got hormones running through my system," she said. "That is why I sit wriggling, saying I want to have a baby." (People) -- BDV-112980-BDV