Michelle Obama congratulates duke and duchess of Cambridge on royal baby

Former first lady Michelle ObamaMichelle LeVaughn Robinson ObamaObamas greeted by screaming fans at Martha's Vineyard Kamala Harris tied with Bernie Sanders as betting favorite for 2020 Dems The Hill's Morning Report — Election Day drama for Trump MORE on Monday posted a message of congratulations to the the United Kingdom's duke and duchess of Cambridge, Prince William and Kate Middleton, on the birth of their new baby.

On her Instagram page, Obama posted a photo from a past visit with the royal family, featuring former President Obama, William and Prince George, the oldest child of William and Kate. The photo, in which George is wearing a bathrobe, went viral after the 2016 visit.

“Barack and I are thrilled to congratulate The Duke and Duchess of Cambridge on their newest arrival!” she wrote. “We hope to meet him soon for a Kensington Palace pajama party. I’ll wear my robe!”

Kate gave birth Monday to a boy, who is now fifth in line to the British throne.

The Obamas are close with the William and his brother, Prince Harry, but will not attend Harry's wedding to American actress Meghan Markle next month, as the couple has decided not to have any official political leaders as guests.