The upcoming royal baby will be referred to as "Her Highness" and "Princess" if it ends up being a girl, announced the Queen Thursday, ending a tradition that dates back to George V that dictates only male royal progeny would receive the titular title of "Prince."
Queen Elizabeth announced that she had issued a Royal Letters Patent that changed the old convention, which had been in place since 1917, under the reign of George V, writes the BBC.
The Royal Letters Patent was released to the public in the London Gazette, as per tradition.
The Letters Patent reads like this, per the BBC: "All the children of the eldest son of the Prince of Wales should enjoy the style, title and attribute of Royal Highness with the titular dignity of Prince or Princess prefixed to their Christian names."
Prior to the change, female offspring of the two would instead have been given the title of "Lady," writes the Mirror.
It's another move towards gender parity in England's royal family, which announced last year that the eldest child of the Duchess of Cambridge and the Duke of Cambridge will become the future symbolic ruler of the realm — whether it's a girl, or a boy.
Previously, male offspring could "skip the line" to the crown over their elder sisters, a tradition that had become archaic in the 21st century world.
"I think they're fully aware of the fact that our most successful monarchs have been women – Elizabeth I, Queen Anne, Queen Victoria, our own queen," said royal historian Robert Lacey to the Guardian, regarding the new primogeniture move.
"In a modern society, where the royals have psychic power rather than actual power, it's all about keeping the monarchy in business – and they know that a woman will probably do that better than a man," he added.
Middleton turned 31 on Wednesday — the same day as the Queen's announcement — and marked the date in a quiet home celebration with her husband and the royal family.