Crown Princess Mary of Denmark

Crown Princess Mary of Denmark is photographed on her 40th birthday, Feb. 5, 2012.

Denmark's Crown Prince Frederik and Crown Princess Mary attend a jazz concert at the Flagey building in Brussels on Jan. 26, 2012.

Before she became a princess, Mary Elizabeth Donaldson was an Australian advertising executive turned estate agent. She met Frederik, the heir to the Danish throne, at a bar in Sydney during the 2000 Summer Olympics. They married on May 14, 2004.

Denmark's Crown Prince Frederik, right, and Australian-born Crown Princess Mary pose with their twins Princess Josephine (held by Mary) and Prince Vincent (held by Frederik) during a visit to Admiralty House in Sydney on Nov. 20, 2011, for a visit to Australia's Governor General Quentin Bryce.

The twins were born on Jan. 8, 2011. Frederik and Mary are also parents to Prince Christian, born in 2005, and Princess Isabella, born in 2007.

Crown Princess Mary of Denmark and husband Crown Prince Frederik of Denmark attend the religious ceremony of the royal wedding of Prince Albert II of Monaco to Princess Charlene of Monaco in the main courtyard at the Prince's Palace on July 2, 2011, in Monaco.

Crown Princess Mary and Crown Prince Frederik of Denmark with Princess Isabella and Prince Christian pose after the christening of their twins, Prince Vincent and Princess Josephine, at Holmens Kirke on April 14, 2011, in Copenhagen, Denmark.

Crown Prince Frederik and Crown Princess Mary of Denmark attend the wedding of Crown Princess Victoria of Sweden and Daniel Westling on June 19, 2010, in Stockholm, Sweden.

Danish Queen Margrethe, center, waves to the crowd with members of the royal family from left, Crown Princess Mary, Prince Consort Henrik, Princess Marie with Prince Henrik, Prince Joachim, Prince Felix and Prince Nikolai at the balcony of Amalienborg Palace in Copenhagen, Denmark, Friday, April 16, 2010.

Danish Crown Princess Mary, left, Crown Prince Frederik, second left, and Queen Margrethe, right, welcome first lady Michelle Obama, second right, at Amalienborg Castle in Copenhagen, Denmark, on Oct. 1, 2009.

Crown Princess Mary of Denmark is greeted by well-wishers as she visits the northern German city of Flensburg on May 6, 2009.

Crown Prince Frederik, Crown Princess Mary, Prince Christian and Princess Isabella of Denmark are shown during a media call at Government House on Sept. 4, 2008, in Sydney, Australia.

Crown Prince Frederik and Crown Princess Mary of Denmark arrives to attend the wedding between his brother Prince Joachim of Denmark and Marie Cavallier on May 24, 2008, at the Mogeltonder church in Mogeltonder, Denmark.

Princess Mary of Denmark holds her daughter Princess Isabella of Denmark at the Fredensborg Palace Church for the baby's christening on July 1, 2007, in Frendensborg, Denmark.

Princess Mary of Denmark waves as she arrives for H.M. King Carl XVI Gustaf's private dinner to celebrate his 60th birthday at Drottningholm Palace on April 29, 2006, in Stockholm, Sweden.

Crown Prince Frederik and Crown Princess Mary of Denmark pose with their new baby son as they leave Copenhagen University Hospital on Oct. 18, 2005, in Copenhagen, Denmark. The baby was born on Oct. 15.

Crown Princess Mary of Denmark attends a press conference at the Hobart Government House on March 11, 2005, in Hobart, Australia.

Crown prince Frederik and Crown Princess Mary of Denmark wave to wellwishers from the balcony at Amalienborg castle in Copenhagen, on May 14, 2004, after their wedding ceremony at Copenhagen's cathedral.