Hollywood stars Joaquin Phoenix, 45, and Rooney Mara, 35, have reportedly welcomed a son named after Phoenix's late brother River.
Russian film-maker Victor Kossakovsky announced the news at a question-and-answer session at the Zurich Film Festival, following a screening of Gunda, a film which Phoenix worked on as an executive producer.
Apologising for Phoenix's absence at the festival, Kossakovsky said: "He just got a baby. His name isRiver, so he cannot promote it now."
The name River also belonged to Phoenix's late brother, who died of a drug overdose in 1993 at the age of 23. River Phoenix, the star of films such as Stand By Me (1986) and My Own Private Idaho (1991), overdosed outside famous nightclub The Viper Room in West Hollywood. Joaquin, then 19, was with him at the time and called 911.
When Joaquin Phoenix won the Best Actor Oscar earlier this year for Joker (2019), he paid tribute to his brother by quoting the lyrics he wrote, which said "run to the rescue with love and peace will follow".
Mara and Phoenix met on the 2013 film Her, but started dating only in 2016, after the filming of Mary Magdalene. They confirmed their engagement last year, but are yet to be married.
There were rumours earlier that Mara was pregnant.