The Duke of Edinburgh has two children also impacted, Lady Louise and James, Earl of Wessex
Prince Edward has moved down the line of succession after the announcement that Princess Eugenie has given birth to her third child.
Buckingham Palace confirmed on Tuesday evening that King Charles's niece welcomed a baby girl in Lisbon, Portugal, on August 3.
The baby girl is 15th in line to the throne, meaning her great-uncle, Prince Edward, will move down to 16th place.
As a result, his two children, James, Earl of Wessex, 18, and Lady Louise Mountbatten-Windsor, 22, will move down to 17th and 18th place, respectively.
Despite being older than her brother by four years, Louise is behind James in the line of succession because they were born before the Succession to the Crown Act 2013.
Under the historical rules that applied at their births, younger sons took precedence over their older sisters.
Princess Eugenie's new baby will be a younger sister to August Brooksbank, five, and Ernest Brooksbank, three.
In a new statement, the Palace said: "Her Royal Highness Princess Eugenie and Mr Jack Brooksbank are delighted to announce the safe arrival of their daughter, born on Monday, 3rd August 2026, at 6.20pm, at a hospital in Lisbon, Portugal.
"Their Majesties The King and Queen and other members of The Royal Family were delighted to be informed of the news."
It is understood that Eugenie and her daughter are doing well following the birth on Monday.
GB News also understands that the royal couple are taking time to decide on the name of their new daughter while the family enjoys spending time together with August and Ernest.
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Princess Eugenie, 36, took to Instagram with a photograph of her third child with the caption: "Jack and I are so excited to announce Baby Girl Brooksbank!! We are beyond in love with our girlie."
The photograph, captured by Mr Brooksbank, showed the baby girl in a pale pink babygrow and a white cap decorated with hearts and stars.
The Brooksbanks split their time between Ivy Cottage in Kensington Palace and a private residence in Portugal.
Mr Brooksbank works in sales, marketing, and promotion for Mike Meldman’s Discovery Land Company, helping to manage and market the luxury CostaTerra Golf and Ocean Club development in Comporta.
The official Royal Family social media account, which usually reserves posts for working members of the monarchy, publicised the news at 6:07pm.
Princess Eugenie, though styled Her Royal Highness, does not carry out engagements on behalf of King Charles.
She and her older sister, Princess Beatrice, instead receive salaries in the private sector while supporting the Royal Family at occasions such as Easter and Christmas.
The daughters of Andrew Mountbatten-Windsor and Sarah Ferguson were provided HRH titles by birthright as legitimate granddaughters of Queen Elizabeth II through the male line, under rules set by King George V in 1917.
Princess Eugenie works as a director at the contemporary art gallery Hauser & Wirth in London.
This is a position she has held since 2017 after joining the firm in 2015.
