Prince William and Duchess Kate's babies: See how all their debuts compare

Prince William and Duchess Kate are some cool customers. Just seven hours after the Duchess gave birth to her third child, a son, the parents of three emerged from the Lindo Wing of St. Mary's Hospital in London with Kate holding their little prince in her arms. Debuting their newborn at the hospital is a tradition they've followed with each of their children. To celebrate Prince Louis's arrival, Wonderwall.com is taking a look at the royal baby debuts for all of the Duke and Duchess of Cambridge's children. On April 23, of course, the new parents were full of excitement as Duchess Kate, wearing a knee-length red dress, and Prince William revealed their bundle of joy to the public. While getting into a waiting car, Will told reporters that he and Kate are "very happy" but also "thrice worried now." Keep reading to see more shots of the couple with Prince Louis plus Prince George's hospital debut in 2013 and Princess Charlotte's debut in 2015 too…

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Prince William and Duchess Kate leave St. Mary's Hospital in London with newborn son Prince Louis on April 23, 2018.

Prince William and Duchess Kate leave St. Mary's Hospital in London with their newborn baby boy, Prince Louis, on April 23, 2018.

After the birth of his third child with Duchess Kate, Prince William returns to the Lindo Wing at St. Mary's Hospital in London with Prince George and Princess Charlotte so they can meet their brother for the first time on April 23, 2018.

Prince William leads Prince George and a waving Princess Charlotte up the stairs of the Lindo Wing at St. Mary's Hospital in London as they prepare to meet their brother on April 23, 2018.

Meet the newest member of the royal family! His Royal Highness Prince Louis of Cambridge.

Duchess Kate and Prince William posed with newborn Princess Charlotte outside the Lindo Wing of St. Mary's Hospital in London on May 2, 2015.

Duchess Kate and Prince William posed with their newborn daughter, Princess Charlotte, outside St. Mary's Hospital in London following her birth on May 2, 2015.

Prince William, Duchess Kate and their newborn baby girl, Princess Charlotte, waved to the public as they left St. Mary's Hospital's Lindo Wing on May 2, 2015.

Prince William kissed Prince George as they arrived at the Lindo Wing of St. Mary's Hospital after Duchess Kate gave birth to a baby girl, Princess Charlotte, on May 2, 2015.

Prince William and Prince George wave to the crowd gathered outside the Lindo Wing at St. Mary's Hospital in London after Duchess Kate gave birth to a baby girl, Princess Charlotte, on May 2, 2015.

Prince William and Duchess Kate departed the Lindo Wing of St. Mary's Hospital in London with newborn son, Prince George, on July 23, 2013.

Prince William put Prince George in his car outside St. Mary's Hospital in London to take him home to Kensington Palace for the first time on July 23, 2013.