Kate, Prince of Prince William, smiled and waved when she left the hospital Monday after the birth of a boy, now fifth in line with the British throne.
The child was born at. 10.01 and weighed 3.8 kg. William was present for the birth at St Mary's Hospital in West London, where their two other children, George and Charlotte, were also born.
Kate, wearing a red dress, smiled at hundreds of well-guardians and total journalists when she left the hospital colliding her baby only seven hours after birth. William later put the boy in a car seat in a waiting car.
"Listen to the worry now," William told reporters and held three fingers with a smile when he entered a Land Rover to take his wife and newborn back to Kensington Palace. "We did not keep you waiting for this time."
"Very happy, very excited, thank you," he said. When asked about a name for the boy, William said, "You'll find out sooner or later." Bookmakers have made Albert, Arthur, Jack and Fred the favored names of a boy.
Queen Elizabeth, Prince Charles, the grandfather of the child and other members of the royal family and Kate's family have been informed and "looking forward to the news," said Kensington Palace.
The child is the sixth grandchild of the queen and is behind his grandfather and heiress Prince Charles, father William and siblings George and Charlotte in line with the throne.
A 2013 change to law means that a new prince for the first time in British history will not replace his older sister in the order. Earlier younger men would take precedence over older female siblings.
William's younger brother Harry, marrying US actress Meghan Markle next month, falls to sixth.
The official announcement of the birth was made by submitting a message to a staff member in the lane of Queen London's home Buckingham Palace, a tradition that has been in place since its official residence in 1837.
William and Kate met as a student at St. Andrews University in Scotland. They marry at Westminster Abbey in April 2011.
The couple now live at Kensington Palace, and last year William made his day job as an air ambulance pilot to concentrate full-time work on royal duties on behalf of his grandmother, having confronted some criticism from British newspapers, calling him "workshy wills".
He has been determined to play a practical role in raising his children while protecting their privacy, a problem close to his heart after his mother's death, Princess Diana, in a car accident in Paris in 1997 when Her limousine sped away from pursuing paparazzi.
"I think he takes much more commitment than he used to," said royal cinema Claudia Joseph.
"But, compared to full-time, full-time members of the public, he still has time to look after the children to give them their bath to put them to bed and I think he will continue to do it. "