News Corp columnist Louise Roberts says she does question the motives of Prince Harry and Meghan Markle amid the name they've chosen for their new baby girl.

It comes as the couple announced the birth of their baby daughter, Lilibet Diana, who was born on Friday morning in Santa Barbara, California.

The couple's second child is named after her great grandmother the Queen and her late grandmother, the Princess of Wales.

Ms Roberts said it is fabulous news that the couple have had a healthy baby girl, however she does "question their motives" in choosing a name for their baby which is "particularly personal to the Queen".

"It's what Prince Philip used to call her," Ms Roberts told Sky News host Chris Kenny.

"There are suggestions out of the UK that she's (the Queen) not entirely happy with them, sort of, hijacking her pet name".