Emily Blunt and John Krasinski are the proud parents of a baby girl, the happy father tweeted.
"Emily and I are so incredibly happy to welcome our daughter Hazel into the world today! Happy bday!" he tweeted.
This is the first child for the 30-year-old actress and the former "Office" star, 33. The couple first announced Blunt was pregnant in September.
Emily Blunt and John Krasinski Expecting a Baby
"It's hard to sum up something that's so vital and means everything to you in a sound bite. Do you know what I mean?" the "Devil Wears Prada" star told Modern Luxury Manhattan magazine in 2012 about her marriage to Krasinski. "All I can say is that it's an effing blast. It's just great, and I'm so happy."
John Krasinski Sounds Off on Life After 'The Office'
The couple, who were married in 2010, had always planned to have children, she said.
"We want to have children; I just don't know when yet," she said at the time. "I'm just not sure about the timing of all of that. We're both from big families so I think it's something we want."