Royal Baby Flashback: See All the First Photo Moments of Prince William and Kate Middleton's Kids

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A look back at all the sweet pics documenting the arrival of the Duke and Duchess of Cambridge's children.

Prince William and Kate Middleton are now the proud parents of three royal kids.

The Duke and Duchess of Cambridge welcomed their third child, a baby boy, in London, England, on Monday, joining 4-year-old Prince George and 2-year-old Princess Charlotte. Now, ET's taking a trip down memory lane and resharing all the sweet first pics of the royal babies.

William, 35, and Kate, 36, first became parents on July 22, 2013, when Prince George was born at St. Mary's hospital in London, England. At the time, Kate wore a beautiful, polka-dot Jenny Packham dress in a powder blue hue, keeping her brunette tresses down with effortless waves. Her husband complemented her look perfectly, sporting a light blue button-down shirt, while baby George was sweetly bundled up in a white lace G.H. Hurt & Son Ltd. wool shawl.

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Nearly two years later, on May 2, 2015, Prince George became a big brother for the first time when his sister, Princess Charlotte, was born at the same hospital. For her only daughter's arrival, the Duchess of Cambridge wore another Jenny Packham number -- a pastel yellow-and-white printed frock -- with her signature nude pumps. Prince William opted for a more casual outfit, donning a blue sweater with navy jeans. Like with Prince George, the royals wrapped their newborn in a cozy white shawl (also from G.H. Hurt & Son Ltd), complete with a matching knit hat.

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Shortly after Charlotte was born, William left the hospital to go pick up George, so he could meet his baby sister. He looked as cute as ever, coordinating outfits with his dad and waving to photographers outside the institution. 

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For the arrival of their third child, whose name has yet to be revealed, Kate stunned in a red dress with a white lace collar by Jenny Packham, paired with her go-to heels and pearl earrings, while Prince William went with blue for a third time. A press release from Kensington Palace revealed the newborn was also wrapped in a shawl from G.H. Hurt and Son Ltd., one very similar to the ones his siblings were presented with when they were born.

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Prince George and Princess Charlotte were also photographed outside the hospital, adorably dressed in blue as a subtle way to honor their baby brother. It appears they were taking a style cue from their mom, who was seemingly giving us clues about the gender of her third baby all along!

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As we patiently wait to hear the moniker Kate and William picked out for their newborn, watch the video below to hear everything we know (so far!) about royal baby No. 3.