Said said she thoroughly enjoyed the experience of labour and childbirth.
The actress welcomed daughter Marlowe, with fiance Tom Sturridge, in July and the star told Harper's Bazaar magazine: "It's the best, the greatest thing in the world... I would do that day a million times again. I would do that day, every day. I loved it."
Sienna revealed she is relishing being a mum.
"It's still the most surreal thing, that you can create, that I grew this life inside my stomach, her eyeballs, everything - every little fibre," said the 30-year-old.
"And I'd expected that she'd be this extension of me and I'd instantly understand who she was because she'd come from me, and then you realise that they are their own people entirely. Very connected to you, of course. But they're their own person."
The actress said she sees her body differently now that she has had a child.
"It's not mine - all the attachment to its flaws or any aesthetic attachment is gone," she explained. "You understand what breasts are for; and I have such enormous respect for my body because of what it can do."