PRINCE William and his wife, Catherine, have announced they are expecting a baby, ending days of speculation the 30-year-old duchess was pregnant.
The announcement came after Kate, 30, was taken late Monday afternoon to King Edward VII Hospital in London where she is expected to remain for several days with severe morning sickness.
The condition is more often experienced by women expecting twins.
William, also 30, drove Kate to hospital after she fell ill while they had been staying at her parents' house in Berkshire, west of London.
The news was met with great joy from the royal households and the general public.
The couple put out a statement saying they were "delighted with the news".
The baby will be born third in line to the throne, thanks to laws changed last year in Britain, and it will be the first time in almost 120 years a serving monarch gets to meet a great grandchild born directly into succession to the crown.
Royal births are usually celebrated with a Royal Salute of 41 guns.
They are registered in the normal way, although the Home Secretary is required to notify certain officials including the Lord Mayor of London, while the Queen's Private Secretary Sir Christopher Geidt informs Governors Generaloverseas.
There is also the age old custom of attaching Notice of Royal births and deaths to the railings at Buckingham Palace for members of the public to read.
But as well as keeping to this tradition, the arrival of royal birth will no doubt also be officially declared via the monarchy's websites, on Facebook and via Twitter.
Joe Little, managing editor of Majesty magazine, said the news bookended a year that saw the royal family riding high in popular esteem after celebrations of Queen Elizabeth II's 60 years on the throne.
"We're riding on a royal high at the moment at the end of the Diamond Jubilee year," he said. "People enjoyed the royal romance last year and now there's this. It's just a good news story amid all the doom and gloom."
Speculation about when Wills and Kate would start a family has been intense since the royal wedding in 2011.
William's mother - the late Princess Diana - got pregnant just four months after her wedding in 1981.
Diana reportedly suffered from morning sickness for months and complained of constant media attention.
"The whole world is watching my stomach," Diana once said.