Joaquin Phoenix and Rooney Mara are said to have become parents to a baby boy, who is named after the actor's late brother.
According to director Viktor Kossakovsky, Joaquin was not able to promote his latest film Gunda — on which he serves as executive producer — because he "just got a baby", and the pair named the little boy after River Phoenix, who died in 1993 aged 23 of combined drug intoxication.
Speaking at the Zurich Film Festival, Viktor said: "He just got a baby, by the way, his name was ... a beautiful son called River, so he cannot promote it [the film] now."
Joaquin, 45, and fellow actor Rooney, 35, are yet to confirm the news publicly, and have never confirmed their pregnancy.
It was reported in May that The Girl with the Dragon Tattoo actress was expecting her first child with the Joker star.
The pair started dating in 2018, and got engaged in July last year.
Joaquin admitted last year that Rooney — who he first met on the set of 2013 movie Her — is the only girl he has ever researched online.
He said: "She's the only girl I ever looked up on the internet.
"We were just friends, e-mail friends. I'd never done that. Never looked up a girl online.
"Rooney said to me the other night, 'Do you realise how many great opportunities you've had? These films?'
"I said it's true, I've been so fortunate, so many movies where I was like, I don't know if I'll ever be able to top this experience. The experience of making this movie. It was incredible that I found another one." — BANG