The Duchess of Cambridge and husband Prince William welcomed their second child on 2 May at 8.34am.
The girl, as yet unnamed, is fourth in line to the throne.
Kensington Palace announced the birth this morning, saying: "Her Royal Highness The Duchess of Cambridge was safely delivered of a daughter at 8.34am.
"The baby weighs 8lbs 3oz. The Duke of Cambridge was present for the birth.
"The Queen, The Duke of Edinburgh, The Prince of Wales & The Duchess of Cornwall, Prince Harry & members of both families have been informed.
"Her Royal Highness and her child are both doing well."
They announced she was in labour this morning, and she gave birth after a two-and-a-half-hour labour.
Her Royal Highness The Duchess of Cambridge was safely delivered of a daughter at 8.34am.— Kensington Palace (@KensingtonRoyal) May 2, 2015
As with first son George, the royal couple chose not to learn their child's gender ahead of the birth.
Once again, the world's eyes will be on the Lindo Wing at the St. Mary's Hospital in Paddington, London as we await the first glimpse at the royal baby soon.
It's the same hospital where Kate gave birth to the couple's first son, George, in July 2013.
Traditionally a royal birth is announced in the following way: the medical staff sign an official birth announcement that is taken by a royal aide - via police escort - to Buckingham Palace where it is attached to an easel for the public to see.
Kate and William announced the pregnancy in September 2014, but as with Prince George, poor Kate was laid low with hyperemesis gravidarum, a severe form of pregnancy sickness.
When she was pregnant with George, she was treated at hospital, but this time she was treated by medics at Kensington Palace in London.
The sickness meant Kate had to pull out of several engagements including the Invictus Games opening night and a trip to Malta which would have been her first solo public engagement overseas.
Kate, 33, finally made her first post-pregnancy announcement on 21 October, when she joined her husband to welcome the President of Singapore, Tony Tan, to the UK.
Since then, she has carried out a string of engagements across the UK – with the world's eyes on her blossoming baby bump! She also took part in a visit to New York with William in December. Her final day of engagements before maternity leave was on Friday, 27 March, when she joined Prince William in South London.
The newborn baby is fourth in line to the throne after grandfather Prince Charles, father Prince William and brother Prince George.
New rules on the royal line of succession came into force earlier this year meaning had the baby been male or female, they would have been fourth in line to the throne regardless. Previously, a baby girl would have been overtaken by future brothers.
In honour of the new royal baby, we look back at some of little George's cutest outfits!
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