Kate Middleton Pregnant: Duchess of Cambridge Expecting Second Royal Baby

The Duke and Duchess of Cambridge are expecting their second child.

Prince George is set to become a big brother as the royal couple announce that Kate Middleton is pregnant.

Speculation has been rife, well ever since Prince George was born in July 2013, that Kate and William were keen to add to their young family.

Clarence House annouced the happy news at 10.27am this morning, tweeting:

"The Duke and Duchess of Cambridge are very pleased to announce that The Duchess of Cambridge is expecting their second child.

"The Queen and members of both families are delighted with the news that Their Royal Highnesses are expecting their second child."

Kate and William may have announced the news today as they were due to make an official appearance at Oxford University today to open The Dickson Poon University of Oxford China Centre Building but thanks to morning sickness the Duchess was be unable to attend.

"As with her first pregnancy, The Duchess is suffering from Hyperemesis Gravidarum," according to Clarence House.

"The Duchess of Cambridge is being treated by doctors at Kensington Palace."

William has attended the opening solo and has said he's "thrilled" at the news, despite a tricky week for poorly Kate who is thankfully "feeling okay".

Prime Minister David Cameron has been one of the first to offer his congratualtions to the royal couple:

"Many congratulations to the Duke and Duchess of Cambridge. I'm delighted by the happy news that they're expecting another baby."

No word yet on whether Prince George will be having a little brother or sister but no doubt the little one will be just as cute as their brother.

The second-born 'spare to the heir' royal will be fourth in line to the throne, however.

The 32-year-old suffered from Hyperemesis Gravidarum during her first pregnancy, which sees expectant mothers experience relentless vomitting and nausea that lasts past the first trimester.

Though unpleasant, hyperemesis doesn’t signal that there’s anything wrong with the pregnancy or baby and with medical support, most women do find ways to cope and get by.

Morning sickness is very common, with around 70 per cent of pregnant women experiencing it, but hyperemesis affects just two per cent of pregnancies. It varies in severity but can cause relentless vomiting and nausea and lead to weight loss. And unlike morning sickness, hyperemesis frequently continues after the first trimester.

Bookies are already taking bets as to the sex and name of the little royal, with Coral claiming Alexandra is the favourite for a girl (5-1) with James being tipped for a boy (3-1).

There is also a 100-1 shot that Kate is expecting triplets, but we won't be putting money on that any time soon!