Zara Phillips and Mike Tindall are expecting a baby in the New Year, Buckingham Palace announced today.
The announcement comes amid the hotly anticipated arrival of the Duke and Duchess of Cambridge's first baby, which is expected to arrive in the coming days.
Buckingham Palace said in a statement: "Mr and Mrs Mike Tindall are very pleased to announce that Zara Tindall is expecting a baby in the new year.
"The Princess Royal and Captain Mark Phillips, Mr Phillip and Mrs Linda Tindall, and members of both families are delighted with the news.
"This baby will be the first child for Mike and Zara and the third grandchild for the Princess Royal."
Queen Elizabeth II's granddaughter Zara married England rugby star Tindall in July 2011 at Edinburgh's Canongate Kirk and a reception at the Queen's Scottish residence, the Palace of Holyrood.
Phillips, a keen sportswoman, was pictured just days ago competing on her horse CG Master Lux in the show jumping phase of the Barbury International Horse Trials at Barbury Castle Estate, Rockley.
The royal took a tumble while competing but she was described as "fine" by a spokeswoman for Juniper Sport, a PR and sports agency that represents her
Asked if Zara still had the next Olympics on her schedule now she was a prospective mother the spokeswoman said: "She can still compete, it totally depends on horses and whether she feels it's appropriate.".
David Cameron's official spokesman described the announcement as "quite terrific news", telling reporters: "The Prime Minister will send his very, very best wishes to the happy couple."