Princess Beatrice’s baby will inherit a unique title - while her sister Eugenie’s child will not.
In Beatrice’s case, though the gender is not yet known, the baby will be granted a title upon birth due to her husband, Edoardo Mapelli Mozzi.
Edoardo is an Italian count - meaning their children will be granted the title of count or nobile donna, depending on whether they are a boy or girl.
Beatrice, 32, gained the title of Italian countess when she married Mr Mapelli Mozzi, 38, ten months ago.
However in Eugenie's case, her husband Jack Brookbank, who doesn’t have a title, cannot pass one onto their son August.
Speaking to the Daily Mail, Mr Mozzi’s father, Count Allessandro Mapelli Mozzi, said: “Edoardo is the only male descendent taking the family into the next generation.
“He is a count, his wife will be a countess automatically and any of their children will be counts or nobile donna.”
Buckingham Palace announced Princess Beatrice and her husband, Edoardo Mapelli Mozzi, were expecting a baby later this year.
In a statement, the Palace said: “Her Royal Highness Princess Beatrice and Mr Edoardo Mapelli Mozzi are very pleased to announce that they are expecting a baby in autumn of this year.
“The Queen has been informed and both families are delighted with the news.”
The baby will be the Queen's 12th great-grandchild following the arrival of the Sussexes' second child in the summer.
Beatrice married Edoardo in a secret lockdown wedding in Windsor back in July, with the Queen, Prince Philip, Sarah Ferguson, Prince Andrew and Princess Eugenie among the small group of guests.
The couple's original wedding had to be scrapped due to lockdown, however they opted to have a secret ceremony behind closed doors as soon as government restrictions allowed.
Her father the Duke of York walked her down the aisle and hosted a reception at his home The Royal Lodge, Windsor.
Edoardo's toddler son Wolfie was best man and pageboy.
Beatrice, who is ninth-in-line to the throne, borrowed one of the Queen's dresses for the special day, which she teamed with a stunning diamond tiara.
