John Stamos congratulates Ashley Olsen on birth of baby boy

John Stamos has congratulated his former Full House co-star Ashley Olsen on the recent birth of her baby boy.

The child star-turned-fashion designer and her artist husband Louis Eisner reportedly became parents to a son named Otto in New York earlier this year, according to reports published last week.

On Thursday, Ashley's Full House co-star John congratulated her on her new arrival via Instagram, writing, "Congratulations to Ashley and her husband, Louis, who welcomed their baby boy last week."

In the rest of the caption, John, 60, reflected on his longtime friendship with Ashley, 37, and her twin sister Mary-Kate.

"Watching Mary-Kate and Ashley grow into the incredibly bright and remarkable women they are today has been one of the greatest joys of my life," he wrote. "If you would have told me those blue-eyed babies I met on set nearly 40 years ago would still be in my life at 60 years old, I wouldn't have believed you. I am blessed."

Mary-Kate and Ashley began their acting career at the age of nine months, with them sharing the role of Michelle Tanner on Full House alongside John as Uncle Jesse between 1987 and 1995.

He accompanied his message with a montage of clips showing his friendship with the "two adorable munchkins" over the years. The video included a section from the audiobook of his upcoming autobiography If You Would Have Told Me: A Memoir.

"I'm young but I really want kids someday and these lovely little girls so bouncy and bright represent the best versions of future dreams," he gushed. "I take them to Disneyland, I adore them, giving them kisses on top of their head, buy them a few c**ppy souvenirs and then hand them back to their parents to do the hard work.

"The little kids that were supposed to be background noise grow up to become the kind of humans I hope to have one day. They are precious, delightful and bright. I adore them."