The America actress, who starred in The Dark Knight, has named her second daughter with husband, Peter Sarsgaard, Gloria Ray.
Her spokesperson confirmed the news and the name to People magazine in the States, but no other details have been released.
The couple are already parents to five-year-old Ramona.
Speaking to US magazine before the birth, dad Peter said they had found out they were expecting a girl so they could start thinking about names, saying: "It's the nice thing about knowing the gender of a child. You don't have to call it 'it,' which gets really weird after seven months in.
"So we've been trying out a few names, but nothing solid."
Congratulations Maggie and Peter.
Do you like the name Gloria Ray?