We were already excited about the news that Leighton Meester had become a mum, but now that we know more details we're truly smitten.
Leighton and her husband Adam Brody are proud parents to a baby girl, who they've named Arlo Day.
And contrary to earlier reports, little Arlo in fact arrived in early September, not last week.
A copy of the birth certificate obtained by TMZ today shows that the couple welcomed their new arrival at Whittier Hospital in Los Angeles on September 4.
Thankfully Arlo won't have to deal with a multi-syllable surname, as her parents have just given her the last name Brody. Phew!
News of Leighton and Adam's pregnancy first went public back in March, when the actress was spotted in LA with a large baby bump:
The couple first met on the set of their 2011 film The Oranges, and married in a secret ceremony last year.
Chatting to fans last year, Adam seemed more than ready to become a dad. When asked how many kids he'd like, the actor responded, "I say twelve. And I decide."
As for Leighton, she too happily chatted about motherhood in a 2014 interview, saying many of her friends had settled down too.
"Most people I know are starting to get married," she admitted in Nylon magazine.
"It'll be kids next. I like the grown-up stuff. I like having a house. I've got dogs."