Kate and William Announce the Arrival of Their Baby Girl!

Prince William and Princess Kate Middleton have welcomed a daughter. Photo: Getty Images

All hail the spare!

Princess Kate and Prince William welcomed a little princess, Kensington Palace has announced. The newborn is the royal couple's second child and a little sister for Prince George, 21 months.

The new baby is fourth in line to the throne, behind grandfather Prince Charles, dad William and big brother George.

William, 32, and Kate, 33, left George with nanny Maria Borrallo and arrived at the Lindo Wing of St. Mary's hospital in London on Saturday morning at 6 a.m. after Kate went into labour.

Per royal protocol, an official announcement will be posted with the full details on an easel in the forecourt of Buckingham Palace – just as happened when Prince George was born on July 22, 2013.

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It's expected that close relatives – led by Kate's parents, Carole and Mike Middleton, and William's father Prince Charles and his wife Camilla, Duchess of Cornwall – will come to see the couple and their as-yet-unnamed newborn before the young family leaves the hospital.

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The baby was delivered by a team led by consultant obstetrician Guy Thorpe-Beeston and royal gynecologist Alan Farthing.

Following the celebratory formalities, including a gun salute in one of the London parks, the couple is expected to take their baby home to nearby Kensington Palace, where reigning monarch (and great-grandma) Queen Elizabeth may then visit.

As the couple takes in their first moments with the new baby, royal fans have gathered outside the hospital in hopes of another mini press conference like the one William and Kate held to debut George.

The birth follows weeks of building royal baby fever, as bookmakers ran races of royal favorite corgis to guess the baby's gender while fans wagered on possible names.

Now that the gender is known, the name should follow in the coming days.

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