"Mom and baby are doing well," Thurman's rep told the magazine. The baby's name has not yet been made public.
This is Thurman's her first with her financier boyfriend Arpad Busson, who is already a father to sons Flynn, 14, and Cy, 9, with ex-fiancée Elle MacPherson.
The new addition to Thurman's family joins her children Maya, 13, and Levon, 10, with whom she shares custody with ex-husband Ethan Hawke. Hawke has expanded his family in recent years as well. After marrying his and Thurman's onetime nanny Ryan Shawhughes in 2008, the happy couple has welcomed two children of their own: Clementine, 3, and Indiana, 6 months.
Thurman and Busson began dating in 2007 and, despite a brief separation in 2009, have been together since.
The actress was most recently seen in Robert Pattinson's steamy period piece "Bel Ami," and the TV series "Smash." Speaking to her experience filming several steamy scenes with Pattinson, Thurman revealed to MTV News that the "Twilight" heartthrob was a total and complete professional.
"Robert Pattinson is, I think, going to be a really serious actor," she told us. "I think he's incredibly concrete in his presence on the set and obviously is very handsome. [He] is a very nice person, and he's sensitive. He's present. ... He's a really good actor."
Thurman currently has several films in the works, including the romantic sports-centric comedy "Playing the Field," opposite Gerard Butler, Dennis Quaid and Jessica Biel, which is scheduled for release in December.
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