LONDON (AFP) - Queen Elizabeth II's granddaughter Zara Phillips gave birth to a baby girl on Friday, Buckingham Palace announced - a first child for the champion horse rider and her rugby star husband Mike Tindall.
The little girl, who has yet to be named, arrives five months after Britain's other royal baby - Prince George, born to Phillips' cousin Prince William and his wife Kate.
"Mrs Michael Tindall today safely delivered a baby girl," Buckingham Palace said in a statement.
"Mr Tindall was present at the birth. The weight of the baby was 3.5kg," it added.
The baby is the queen's fourth great-grandchild and is 16th in line to the British throne. Her name will be announced in due course, the palace said.
The new mother, who is the youngest child of the queen's daughter Princess Anne and her ex-husband Mark Phillips, gave birth at Gloucestershire Royal Hospital in the city of Gloucester, south-west England.
Tindall, a former England centre and a 2003 World Cup winner, currently plays and coaches for English Premiership club Gloucester.
He posted on Twitter: "Thanks so much for all your kind messages. Definitely the best day of my life today, so happy! The girls are both doing great!"
The palace said the queen and her husband Prince Philip were "delighted with the news", while Prime Minister David Cameron tweeted: "Many congratulations to Zara and Mike Tindall on the birth of their baby girl."
Like her mother, the baby will not bear a royal title and will be known as plain "Miss Tindall".
Phillips, whose parents are both former professional horse riders, followed in their footsteps by becoming a world-class three-day eventer, winning the world championship in 2006.
She won a silver medal at the London 2012 Olympics and is planning to take part in the Rio de Janeiro Games in 2016.
Phillips sparked controversy by continuing to ride into her pregnancy, though she stopped in the later months.
Tindall has not played for England since the team's woeful performance at the 2011 World Cup in New Zealand.
He made global headlines after he was filmed cuddling up to an old flame at a bar during the tournament - just weeks after his wedding - while his teammates were enjoying a "dwarf-tossing" contest.
Captain at the time, Tindall was fined and dropped from the England squad for his drunken antics, but was later reinstated.
When his wife's pregnancy was announced in July, he joked on Twitter that he hoped his child would not inherit his nose, which has been broken eight times during his career.
Phillips's eventing teammates also spoke of their delight at the new arrival.
"A future Olympian no doubt in years to come," said Mary King.
Bookmakers are offering odds of 50/1 that the baby will one day represent Britain at the Olympics, or 33/1 that she will play international rugby.