Britain's Prince William, Duke of Cambridge and his wife Kate, the Duchess of Cambridge, and their children Prince George and Princess Charlotte walk on the tarmac of the Airbus compound prior boarding their plane in Hamburg, northern Germany, on July 21,2017.
 The British royal couple are on the last stage of their three-day visit to Germany. / AFP PHOTO / POOL / Christian Charisius        (Photo credit should read CHRISTIAN CHARISIUS/AFP/Getty Images)
CHRISTIAN CHARISIUS/AFP/AFP/Getty Images
Britain's Prince William, Duke of Cambridge and his wife Kate, the Duchess of Cambridge, and their children Prince George and Princess Charlotte walk on the tarmac of the Airbus compound prior boarding their plane in Hamburg, northern Germany, on July 21,2017. The British royal couple are on the last stage of their three-day visit to Germany. / AFP PHOTO / POOL / Christian Charisius (Photo credit should read CHRISTIAN CHARISIUS/AFP/Getty Images)
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WINDSOR, ENGLAND - APRIL 17: The Duke of Edinburgh's coffin, covered with His Royal Highness's Personal Standard is carried to the purpose built Land Rover during the funeral of Prince Philip, Duke of Edinburgh at Windsor Castle on April 17, 2021 in Windsor, England. Prince Philip of Greece and Denmark was born 10 June 1921, in Greece. He served in the British Royal Navy and fought in WWII. He married the then Princess Elizabeth on 20 November 1947 and was created Duke of Edinburgh, Earl of Merioneth, and Baron Greenwich by King VI. He served as Prince Consort to Queen Elizabeth II until his death on April 9 2021, months short of his 100th birthday. His funeral takes place today at Windsor Castle with only 30 guests invited due to Coronavirus pandemic restrictions. (Photo by Adrian Dennis/WPA Pool/Getty Images)
Adrian Dennis/WPA Pool/Getty Images
WINDSOR, ENGLAND - APRIL 17: The Duke of Edinburgh's coffin, covered with His Royal Highness's Personal Standard is carried to the purpose built Land Rover during the funeral of Prince Philip, Duke of Edinburgh at Windsor Castle on April 17, 2021 in Windsor, England. Prince Philip of Greece and Denmark was born 10 June 1921, in Greece. He served in the British Royal Navy and fought in WWII. He married the then Princess Elizabeth on 20 November 1947 and was created Duke of Edinburgh, Earl of Merioneth, and Baron Greenwich by King VI. He served as Prince Consort to Queen Elizabeth II until his death on April 9 2021, months short of his 100th birthday. His funeral takes place today at Windsor Castle with only 30 guests invited due to Coronavirus pandemic restrictions. (Photo by Adrian Dennis/WPA Pool/Getty Images)
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LONDON, ENGLAND - OCTOBER 31:  Prince Harry, Prince Phillip and Prince William enjoy the atmosphere during the 2015 Rugby World Cup Final match between New Zealand and Australia at Twickenham Stadium on October 31, 2015 in London, United Kingdom.  (Photo by Phil Walter/Getty Images)
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LONDON, ENGLAND - OCTOBER 31: Prince Harry, Prince Phillip and Prince William enjoy the atmosphere during the 2015 Rugby World Cup Final match between New Zealand and Australia at Twickenham Stadium on October 31, 2015 in London, United Kingdom. (Photo by Phil Walter/Getty Images)
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LONDON, UNITED KINGDOM - APRIL 10: The Honourable Artillery Company fire a gun salute at The Tower of London on April 10, 2021 in London, United Kingdom.  The Death Gun Salute will be fired at 1200 marking the death of His Royal Highness, The Prince Philip, Duke of Edinburgh. Across the country and the globe saluting batteries will fire 41 rounds, 1 round at the start of each minute, for 40 minutes. Gun salutes are customarily fired, both on land and at sea, as a sign of respect or welcome. The Chief of the Defence Staff, General Sir Nicholas Carter, said "His Royal Highness has been a great friend, inspiration and role model for the Armed Forces and he will be sorely missed." (Photo by Chris Jackson/Getty Images)
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LONDON, UNITED KINGDOM - APRIL 10: The Honourable Artillery Company fire a gun salute at The Tower of London on April 10, 2021 in London, United Kingdom. The Death Gun Salute will be fired at 1200 marking the death of His Royal Highness, The Prince Philip, Duke of Edinburgh. Across the country and the globe saluting batteries will fire 41 rounds, 1 round at the start of each minute, for 40 minutes. Gun salutes are customarily fired, both on land and at sea, as a sign of respect or welcome. The Chief of the Defence Staff, General Sir Nicholas Carter, said "His Royal Highness has been a great friend, inspiration and role model for the Armed Forces and he will be sorely missed." (Photo by Chris Jackson/Getty Images)
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People view flowers left in front of the gate at Buckingham Palace in London, after the announcement of the death of Britain's Prince Philip, Friday, April 9, 2021. Buckingham Palace officials say Prince Philip, the husband of Queen Elizabeth II, has died. He was 99. Philip spent a month in hospital earlier this year before being released on March 16 to return to Windsor Castle.
Matt Dunham/AP
People view flowers left in front of the gate at Buckingham Palace in London, after the announcement of the death of Britain's Prince Philip, Friday, April 9, 2021. Buckingham Palace officials say Prince Philip, the husband of Queen Elizabeth II, has died. He was 99. Philip spent a month in hospital earlier this year before being released on March 16 to return to Windsor Castle.
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WINDSOR, ENGLAND - OCTOBER 12:  Prince Philip, Duke of Edinburgh attends the wedding of Princess Eugenie of York to Jack Brooksbank at St. George's Chapel on October 12, 2018 in Windsor, England.  (Photo by Alastair Grant - WPA Pool/Getty Images)
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WINDSOR, ENGLAND - OCTOBER 12: Prince Philip, Duke of Edinburgh attends the wedding of Princess Eugenie of York to Jack Brooksbank at St. George's Chapel on October 12, 2018 in Windsor, England. (Photo by Alastair Grant - WPA Pool/Getty Images)
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Britain's Prince Philip, Duke of Edinburgh, in his role as Captain General, Royal Marines, attends a Parade to mark the finale of the 1664 Global Challenge on the Buckingham Palace Forecourt in central London on August 2, 2017.  
After a lifetime of public service by the side of his wife Queen Elizabeth II, Prince Philip finally retires on August 2, 2017,at the age of 96. The Duke of Edinburgh attended a parade of Royal Marines at Buckingham Palace, the last of 22,219 solo public engagements since she ascended to the throne in 1952.
 / AFP PHOTO / POOL / HANNAH MCKAY        (Photo credit should read HANNAH MCKAY/AFP/Getty Images)
HANNAH MCKAY/AFP/Getty Images
Britain's Prince Philip, Duke of Edinburgh, in his role as Captain General, Royal Marines, attends a Parade to mark the finale of the 1664 Global Challenge on the Buckingham Palace Forecourt in central London on August 2, 2017. After a lifetime of public service by the side of his wife Queen Elizabeth II, Prince Philip finally retires on August 2, 2017,at the age of 96. The Duke of Edinburgh attended a parade of Royal Marines at Buckingham Palace, the last of 22,219 solo public engagements since she ascended to the throne in 1952. / AFP PHOTO / POOL / HANNAH MCKAY (Photo credit should read HANNAH MCKAY/AFP/Getty Images)
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UNSPECIFIED - UNSPECIFIED: In this handout image provided by Harpo Productions and released on March 5, 2021, Oprah Winfrey interviews Prince Harry and Meghan Markle on A CBS Primetime Special premiering on CBS on March 7, 2021. (Photo by Harpo Productions/Joe Pugliese via Getty Images)
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UNSPECIFIED - UNSPECIFIED: In this handout image provided by Harpo Productions and released on March 5, 2021, Oprah Winfrey interviews Prince Harry and Meghan Markle on A CBS Primetime Special premiering on CBS on March 7, 2021. (Photo by Harpo Productions/Joe Pugliese via Getty Images)
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Britain's Prince George, whose seventh birthday is on Wednesday, is seen in this picture taken by his mother, the Duchess of Cambridge, earlier this month and released July 21, 2020. The Duchess of Cambridge/Handout via REUTERS   THE PHOTOGRAPH MUST NOT BE DIGITALLY ENHANCED, MANIPULATED OR MODIFIED IN ANY MANNER OR FORM AND MUST INCLUDE ALL OF THE INDIVIDUALS IN THE PHOTOGRAPH WHEN PUBLISHED. NO COMMERCIAL OR BOOK SALES. NO SALES. NO RESALES. NO ARCHIVES. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. MANDATORY CREDIT. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. NEWS EDITORIAL USE ONLY. NO COMMERCIAL USE. NO MERCHANDISING, ADVERTISING, SOUVENIRS, MEMORABILIA OR COLOURABLY SIMILAR. NOT FOR USE AFTER 31 DECEMBER, 2020 WITHOUT PRIOR PERMISSION FROM KENSINGTON PALACE.
The Duchess of Cambridge/Reuters
Britain's Prince George, whose seventh birthday is on Wednesday, is seen in this picture taken by his mother, the Duchess of Cambridge, earlier this month and released July 21, 2020. The Duchess of Cambridge/Handout via REUTERS THE PHOTOGRAPH MUST NOT BE DIGITALLY ENHANCED, MANIPULATED OR MODIFIED IN ANY MANNER OR FORM AND MUST INCLUDE ALL OF THE INDIVIDUALS IN THE PHOTOGRAPH WHEN PUBLISHED. NO COMMERCIAL OR BOOK SALES. NO SALES. NO RESALES. NO ARCHIVES. NOT FOR SALE FOR MARKETING OR ADVERTISING CAMPAIGNS. MANDATORY CREDIT. THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY. NO THIRD PARTY SALES. NOT FOR USE BY REUTERS THIRD PARTY DISTRIBUTORS. NEWS EDITORIAL USE ONLY. NO COMMERCIAL USE. NO MERCHANDISING, ADVERTISING, SOUVENIRS, MEMORABILIA OR COLOURABLY SIMILAR. NOT FOR USE AFTER 31 DECEMBER, 2020 WITHOUT PRIOR PERMISSION FROM KENSINGTON PALACE.
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(CNN) —  

Britain’s Prince William and his wife, Catherine, are expecting their third child together, Kensington Palace announced on Monday.

“Their royal Highnesses The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their third child,” the palace statement read.

“The Queen and members of both families are delighted with the news,” it added.

The royal couple with their two children on a three-day tour in Germany on July 21.
CHRISTIAN CHARISIUS/AFP/AFP/Getty Images
The royal couple with their two children on a three-day tour in Germany on July 21.

As with her two previous pregnancies, Kate is suffering from hyperemesis gravidarum, which involves nausea and vomiting more severe than the typical morning sickness many women suffer during early pregnancy.

The illness has forced Kate, 35, to cancel a planned engagement at the Hornsey Road Children’s Centre in London, which had been due to take place on Monday morning. She is being cared for at Kensington Palace, the statement said.

CNN understands the Duchess is not yet past the 12-week mark – when women usually get their first scan – but the couple chose to make the early announcement because of her sickness.

Kate was only a few weeks pregnant with Prince George in 2012 when she had to be hospitalized for the condition leading to an early announcement.

During her second pregnancy, the Duchess was treated at Kensington Palace.

The newest tiny royal will be a sibling to four-year-old Prince George and two-year-old Princess Charlotte – the royal couple’s first two children.

The family toured Canada last year.
Chris Jackson/Getty Images
The family toured Canada last year.

Regardless of whether the child is a boy or a girl, the baby will become the fifth in line to the throne behind big sister Charlotte, bumping Prince Harry down the line of succession.

A change in law after William and Kate wed gave women the same rights of accession to the throne as men.

The child will be Queen Elizabeth’s sixth great-grandchild.

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It’s already a big week for the Cambridges as they prepare for George to start school at Thomas’s Battersea in south London on Thursday.

The family moved back to the British capital this year so that they can take on more royal duties on behalf of the Queen and Prince Philip, who retired from public duties in August.

Kate joined William and Harry as they toured a new memorial garden in honor of their mother, Diana, last week.
KIRSTY WIGGLESWORTH/AFP/Getty Images
Kate joined William and Harry as they toured a new memorial garden in honor of their mother, Diana, last week.

Since 2014, the pair have used Apartment 1A at Kensington Palace in London – which underwent a $7.6 million overhaul in 2014 – as their official residence.

Prince William, 35, had been working as an air ambulance helicopter pilot for the past two years. It was the first time a royal who is in direct line to the throne had taken a civilian job; he donated his salary to charity.