THE families of William and Kate are said to be delighted with the news the Royal couple are expecting a baby.
St James's Palace announced the pregnancy yesterday afternoon.
At the same time it was confirmed that Kate had been admitted to a private hospital for treatment for a severe form of morning sickness known as hyperemesis gravidarum.
The St James's Palace statement read: "The Duchess was admitted this afternoon to King Edward VII Hospital in central London with hyperemesis gravidarum.
"As the pregnancy is in its very early stages, Her Royal Highness is expected to stay in hospital for several days and will require a period of rest thereafter."
St James's Palace would not say when the royal couple became aware of the pregnancy, only saying "recently".
It is understood the pregnancy has not passed the 12-week point and the announcement was prompted by the Duchess's medical condition.
For women with hyperemesis gravidarum their vomiting can be so severe they cannot keep food or liquid down.
The condition usually continues past the first three months of pregnancy and can pass by week 21, but may also last longer.
The baby news sparked thousands of goodwill messages on social networks such as Twitter.
Neath mezzo-soprano Katherine Jenkins tweeted: "What lovely news!! Congratulations to the Duke & Duchess of Cambridge!! #PitterPatter"
Also reacting on Twitter, Prime Minister David Cameron wrote: "I'm delighted by the news that the Duke and Duchess of Cambridge are expecting a baby. They will make wonderful parents."
Labour leader Ed Miliband tweeted: "Fantastic news for Kate, William and the country."
A spokeswoman at Kate's old prep school, St Andrew's in Pangbourne, Berkshire — where she showed off her hockey skills last week in an Alexander McQueen frockcoat and three-inch-high calf-length boots — said they had "no inkling at all" that she was expecting.
She said: "Obviously everyone at St Andrew's are delighted for them both. We're absolutely thrilled."
Kate's visit to her old prep school on Friday afternoon was her last public engagement.
She appeared well and even had lunch at the school with pupils and staff during the two-hour visit.
Hyperemesis gravidarum can be serious but Kate was driven to the King Edward VII Hospital in a car and not an ambulance.
The Duchess had a number of engagements this week, including a visit to London's Docklands on Wednesday for a charity fundraising session on a brokers' trading floor, but they have all been cancelled, said St James's Palace.
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