'Everybody worships him': star, 44, on life with her first boy

Sienna Miller's house has a new favorite, and he's only six months old.

The actor, 44, welcomed a baby boy with her fiancé, Crown alum Oli Green, in May. At the premiere of her new film Madden on Nov. 4, she told E! News how the family has taken to its first boy.

"He's a boy, and he's the first boy, so everybody worships him," she said.

Her eldest, Marlowe, 14, whom she shares with ex Tom Sturridge, is "obsessed" with her new brother, E! reports. Miller also has a 2-year-old daughter with Green.

The couple announced the pregnancy late last year, and in May Miller told E! the baby had arrived. "It's happened," she said. "I have a tiny baby next door." She was "madly in love" with him, she added, though stringing sentences together as a family of five was "a bit challenging."

As for diaper duty, the big sisters are off the hook.

"With pleasure for me, it's the honor of my life to change my son's diaper," Miller said. "There are enough of us that are willing."

She described the baby as "incredibly chilled and gorgeous," adding: "We're so lucky."

Christmas at home

Miller is taking a break after Madden, and she can't wait.

"I am not working after this, so I just get to be at home and snuggle up," she said. "Cozying up with little people at this time of year is heaven."

Her fiancé is half American, she told Extra, and his mom hosts a big Thanksgiving. "I love that holiday," she said. She has hosted full Thanksgiving dinners in New York for anyone without plans, she added, and taken her daughter to see the Rockettes.

Asked whether she'd let her son play football one day, she said: "I gonna say yeah, if he wants to, you know, with a helmet." She'd rather talk soccer, she admitted, but joked that after this film: "Now I'm a Raider."

A very happy set

In David O. Russell's football biopic about John Madden, Miller plays Carol Davis, wife of Raiders owner Al Davis, alongside Christian Bale, Nicolas Cage and Kathryn Hahn.

She worked hard on the "very specific Brooklyn" accent, and told Extra: "I don't think I've had a happier experience making a film than this." She told E! the cast's chemistry "felt magical and very, very real."

"You didn't have a second to get bored on this," she said of Russell's set. "We just laughed and played."

She also filmed her series War, about a divorcing couple, while pregnant. Her advice on divorce? "Don't do it."

Madden opens in select theaters on Nov. 11 and streams on Prime Video from Nov. 18.