Queen Elizabeth II is "delighted" by the news of baby Lilibet's birth.

Meghan Markle gave birth to a baby girl on Friday morning, and she and Prince Harry announced the special name on Sunday: it's Lilibet Diana Mountbatten-Windsor. The first name, of course, was inspired by the Queen, whose family nickname is Lilibet.

The Queen's first reaction to Harry and Meghan's baby Lilibet

On Sunday night, the Royal Family's official Twitter sent a congratulatory message to Harry and Meghan with a first reaction led by Queen Elizabeth.

The Queen is "delighted with the news," the Royal Family wrote, including Prince Charles, Duchess Camilla, Prince William, and Duchess Kate in that feeling.

"Lilibet is Her Majesty's 11th great-grandchild," the message added. And Lilibet is no doubt a special one for the Queen, as her own nickname inspired Harry and Meghan's choice for their daughter's name.

Lilibet: How did Queen Elizabeth get her "family nickname"?

Lilibet is Queen Elizabeth's nickname within her family. It goes back to her childhood, said to come from her inability as a small child to pronounce her own name — making it sound more like "Lilibet."

Lilibet then became a pet name for the future Queen around her parents, and Prince Philip eventually adopted the affectionate name for his wife.

Meghan And Harry's Baby Girl Has Arrived

In their announcements, Prince Harry and Duchess Meghan appear to be calling their daughter "Lili" rather than the full Lilibet, perhaps not unlike Harry and his birth name of Henry.

The middle name then honours Princess Diana, Lili's "beloved late grandmother," the baby announcement said.

You can also see the couple's message reflecting on the first days with their daughter here.

Catherine, Duchess of Cambridge, Prince William, Duke of Cambridge and Prince Edward, Earl of Wessex attend the annual Royal British Legion Festival of Remembrance at the Royal Albert Hall on November 09, 2019 in London, England.

It's probably not what you think...

THIS Is What Prince William Did To Impress Kate!