Britain's Prince WiIliam, the Duke of Cambridge, (L) and his wife Catherine, Duchess of Cambridge, leave the King Edward VII hospital in central London, on December 6, 2012. Prince William's pregnant wife Catherine left a London hospital on Thursday, four days after she was admitted for treatment for acute morning sickness.
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Catherine, Duchess of Cambridge (C) takes part in a day of activities and festivities to mark the occasion of St Andrew's Day at St Andrew's School on November 30, 2012 in Pangbourne, Berkshire, England. The Duchess visited the Pre-Prep School for under-5s, unveiled a plaque to officially open a new artificial turf playing field and met members of the school's hockey team, which she played for during her time as a pupil at the school (1986-1995).
- [WPA Pool/AFP/Getty Images]

LONDON, ENGLAND - JANUARY 08: Catherine, Duchess of Cambridge attends the UK premiere of War Horse at the Odeon Leicester Square on January 8, 2012 in London, England. (Photo by Ian Gavan/Getty Images)
- [Ian Gavan/AFP/Getty Images]

The start of a beautiful fairytale: William and Kate kiss on the balcony of Buckingham Palace in London on their wedding day (April 29, 2011).
- [John Stillwell/AFP/Getty Images]

Before becoming a duchess, Kate Middleton was a normal college student at St. Andrews. Here she is in 2005 at her graduation where she first met Prince William.
- [Bruno Vincent/Getty Images]

Kate looks lovingly at her new husband, Will, during a rodeo in Calgary, Canada on July 7, 2011.
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Prince William and his new wife, Catherine, Duchess of Cambridge, climb aboard a plane of the Royal Canadian Air Force at London's Heathrow Airport, heading to Ottawa, Canada on June 30, 2011. This 12-day North American tour marks their first overseas trip as a married couple.
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Kate, with her own chef's coat, took part in a cooking workshop at the Institut De Tourisme et D'hotellerie Du Quebec on July 2, 2011 in Montreal, Canada.
- [David Rose - Pool/Getty Images]

Catherine, Duchess of Cambridge, donned a striking wide-brimmed hat with flowers at the back for the wedding of Prince William's cousin, Zara Philips, at Canongate Kirk in Edinburgh, Scotland on July 30, 2011.
- [Dylan Martinez/AFP/Getty Images]

Catherine, Duchess of Cambridge, wore a smaller but still eye-catching hat to the Epsom Derby. She sits between her brother-in-law, Prince Harry, left, and her husband, Prince William, right, at Epsom Downs racecourse on June 4, 2011.
- [Matthew Lloyd/AFP/Getty Images]

Kate chose a contemporary hat for an important royal function. The newlyweds are still beaming with happiness on June 13, 2011 as they leave the Order of the Garter Service at St. George's Chapel.
- [Andrew Winning - WPA Pool/Getty Images]

The newlyweds left Buckingham Palace the day after their wedding for a weekend at home before setting off on their private honeymoon.
- [John Stillwell/AFP/Getty Images]

Kate Middleton shakes hands with well-wishers following a visit to Darwen Aldridge Community Academy in Darwen, northwest England, on April 11, 2011.
- [Adrian Dennis/AFP/Getty Images]

The Prince and Duchess arrived on Parliament Hill on Ottawa during Canada Day celebrations that were complete with Canadian guards on July 1, 2011.
- [Timothy A. Clary/AFP/Getty Images]

Kate Middleton and Prince William talk with youngsters from a local soccer club at Witton County Park, during a visit Darwen Aldridge Community Academy on April 11, 2011 in Darwen, northwest England.
- [Alastair Grant/AFP/Getty Images]

Catherine, Duchess of Cambridge, was one of many royal women wearing hats to the private wedding of Prince William's cousin, Zara Philips, to rugby player, Mike Tindall in Scotland. Kate's hat was by far the largest with a simple brim in the front and an elaborate floral design at the base of the hat.
- [Dylan Martinez/AFP/Getty Images]

Prince William and his wife, Catherine, Duchess of Cambridge, helped at the Mission Serve: Hiring Our Heroes event in Culver City, California on Sunday, July 10, 2011, which was their last day on their tour of North America.
- [Mario Anzuoni - Pool/Getty Images]

Catherine, the Duchess of Cambridge, appears much thinner than she did before the royal wedding, just weeks before this meeting between the newlyweds and US President Obama and First Lady Michelle Obama.
- [Charles Dharapak/AFP/Getty Images]

Kate was so proud of her husband's team winning the polo challenge that she kissed him on stage, which is rare to see from the private newlyweds. Meanwhile, Will's teammate and fellow champion, Santi Trotz, teased the couple by sticking out his tongue.
- [Hans Gutknecht - Pool/Getty Images]

Catherine, Duchess of Cambridge arrives at the BAFTA Brits To Watch event held at the Belasco Theatre on July 9, 2011 in Los Angeles, California.
- [Kevork Djansezian/AFP/Getty Images]