EXCLUSIVE: by BAZ BAMIGBOYE

Last updated at 08:39 31 December 2007

Nicole Kidman and her husband of 18 months are expecting their first baby, the Daily Mail can reveal.

The Oscar-winning actress and Keith Urban, the country and western singer she calls the "love of my life", broke the news to their families over the Christmas holiday.

The 40-year-old Australian star had already spoken of "winding down" her film-making activities as much as possible next year.

The baby, whose expected arrival date has not yet been revealed, will be the actress's first natural child.

She adopted Isabella, 14, and twelve-year-old Conor during her first marriage to Tom Cruise.

Miss Kidman was stunned when he filed for divorce in 2001.

Shortly after they split, she revealed that she had suffered an ectopic pregnanacy and a miscarriage during the marriage.

Miss Kidman spent her Christmas holiday in Sydney, after finishing work on Baz Lurhmann's epic romantic adventure film "Australia" on December 21.

She is due to film The Reader with Ralph Fiennes and British director Stephen Daldry in Berlin next month, but has no more cinema work planned after that.

"I just want to spend as much time as possible with my husband," she told the Daily Mail.

Earlier this month the actress also dismissed the idea of returning to the stage next year.

"It wouldn't fit in with the logistics and dynamics of my family," she said - a remark given extra meaning by the news of her pregnancy.

Her most recently-released film is the extravagant fantasy The Golden Compass.

Although the film was attacked by some critics, the actress's performance as the glamorous villain Mrs Coulter won wide praise.

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Miss Kidman married Urban in Sydney in June 2006.

The early months of the marriage were described as difficult as the actress helped her new husband deal with a drink problem.

Urban spent several months in a rehabilitation clinic in the U.S.

Nicole Kidman's most recent film is the extravagant fantasy film The Golden Compass,although the film was attacked by some critics, the actress's performance as the glamorous villain Mrs Coulter won wide praise.

At the film's Australian premiere in Sydney on December 14, Nicole was mocked in some quarters for wearing a silver trouser suit ensemble with a jacket. That suit was most likely carefully chosen to conceal rather than reveal.

Also when the Daily mail visited the set of Australia in Sydney earlier in December the actress was shooting scenes in a long ball gown ,so again, much could be kept out of view.

In between takes on set Nicole took to a bed in one of the studio's dressing room's complaining that she felt 'constantly tired'.