Royal baby: Congratulations pour in for Kate, William

Many wishes have come pouring in for Kate Middleton and Prince William, since they announced the birth of their new son on April 23. Politicians and celebrities alike, welcomed the newest member of the royal family in adorable posts.

Former United States first lady Michelle Obama led the congratulatory messages for the Duke and Duchess of Cambridge. She shared a heartfelt message for Prince William and Kate Middleton's third child, and expressed her wish to meet the little baby soon at a "Kensington Palace pajama party".

"Barack and I are thrilled to congratulate The Duke and Duchess of Cambridge on their newest arrival! We hope to meet him soon for a Kensington Palace pajama party. I'll wear my robe!," the former first lady wrote on Twitter along with a picture of Barack Obama, Prince William, and Prince George.

Her tweet is a reference to the time she visited the Duke and Duchess of Cambridge along with the then United States President Barack Obama, and Prince George wore a fancy bathrobe for the occasion.

Apart from Michelle Obama, there were several others who sent out their regards to the Duke and Duchess of Cambridge.

Canada's Prime Minister Justin Trudeau, along with his wife Sophie Gregoire Trudeau, congratulated Prince William and Kate.

"Canada welcomes a baby boy to the Royal Family! Sophie and I send our congratulations to William and Kate, the Duke and Duchess of Cambridge, and to George and Charlotte on the new arrival," he wrote on Twitter.

Meanwhile, British Prime Minister Theresa May also sent her warmest congratulations to the royal couple.

"My warmest congratulations to the Duke and Duchess of Cambridge on the birth of their baby boy. I wish them great happiness for the future," she wrote on Twitter.

The Mayor of London, Sadiq Khan, sent his regards on behalf of Londoners.

"On behalf of Londoners, I want to send our warmest congratulations to the Duke & Duchess of Cambridge on the birth of their baby boy," he wrote.

Earlier on Monday, Prince William and Kate Middleton appeared on the steps of the Lindo Wing at St. Mary's Hospital to introduce their new baby boy to the world.

Wearing a red dress with a white collar, Middleton looked in good health after giving birth to her as yet un-named prince, who is fifth in line to the throne.

She paid a tribute to her late mother-in-law, Princess Diana, with the choice of her outfit.

When Princess Diana presented Prince Harry to the public, back in 1984, she too wore a red outfit with a white Peter Pan collar.