Ashlee Simpson

Ashlee Simpson-Wentz and husband Pete Wentz welcomed a son Thursday night.

Bronx Mowgli Wentz weighed 7 lbs., 11 oz., and was 20 1/2 inches long.

“Ashlee, Pete and baby Bronx are all healthy and happy, and thank everyone for their well wishes!” a spokesperson says.

Simpson-Wentz, 24, and the Fall Out Boy bassist, 29, announced her pregnancy in May, a few weeks after their opulent Alice’s Adventures In Wonderland-themed wedding.

“I would love to have a big family one day,” Simpson-Wentz told PEOPLE at the time. Added Wentz: “A big soccer team or a band!”

And, as her dad, Joe Simpson, recently said: “The day she found out she was pregnant, she became a woman.”

Wentz, meanwhile, has been leaning on rocker pal Joel Madden – dad to 9-month-old Harlow with girlfriend Nicole Richie – for tips on fatherhood. “Joel gives me advice,” Wentz recently told PEOPLE. “[It's] been really awesome for me to go to another person my age.”

Richie and Harlow were guests at Simpson-Wentz’s Winnie the Pooh-themed baby shower on Nov. 1.

Wentz also has another kind of baby on the way: Fall Out Boy’s third album, Folie A Deux, will be released on Dec. 16.