Kate Winslet has admitted she never even considered giving her new baby the surname RocknRoll, because she is a "grown-up".
The Labor Day actress told Glamour magazine that baby son Bear taking father Ned's surname was not an option.
In an interview with the mag, she said: "We haven't ever really had that conversation; it was always going to have my name. Mia and Joe have it as part of their name, so it would be weird if this baby didn't.
"Of course we're not going to call it RocknRoll. People might judge all they like, but I'm a f***ing grown-up."
Kate, 38, also said that she wouldn't be worrying about losing her post-baby weight: "Having just had a baby, I'm not going to be thinking about my a**e."
She has two other children, Mia Honey from her first marriage to Jim Threapleton and Alfie from her second marriage to Sam Mendes, and was recently criticised by dads' rights group Fathers For Justice for saying: "None of this 50/50 time with the mums and dads - my children live with me; that is it."
The Revolutionary Road star told Glamour she still worried about what people thought of her acting skills.
She said: "Acting is b****y scary. I still have moments when I think 'I can't do this - everybody thinks I'm absolutely s***'."