Sienna Miller has "completely lost" her fashion sense since becoming a mother.

The 44-year-old actress gave birth to her third child, a little boy, in April this year, but admitted that motherhood in her later years has had a negative impact on her sense of style - for which she has become famous.

She told Vogue: "I have completely lost my fashion sense. I've been pregnant or breastfeeding for nearly four years, and I think something happens to the brain - or you're so f****** tired - that you sacrifice your identity.

"You're just 'mother'... and not in the Gen-Z way, as much as I would like to be."

Sienna added that while she knows she has a "good aesthetic", she's been turning to her stylish friends for help with her looks in recent months.

She mused: "I can tell when something's lovely and when it's not, but when it comes to putting clothes together myself, I don't know - I'm just in a strange place. I literally have to text my friends who have great style and ask them to help me."

One such text went to pal Alexa Chung, as Sienna questioned what she should wear to the premiere of Oasis documentary, Oasis: Don't Look Back in Anger.

She said: "I texted her and said, 'I'm going to the Oasis premiere tonight. What do I wear?' And she said, 'If I were blonde, I'd be in a slutty black dress all day long. Find something Carrie Bradshaw and put it with a mule.'

"I replied, 'Googling mule…'.

"I'm just really questioning all this, because I'm just so under-slept and I kind of don't know who I am."

Sienna, who also described herself as a "lactating heifer" in the interview, added: "I also have massive boobs, which I don't know how to dress."

The actress is mum to two kids with fiancé Oli Green, as well as 14-year-old daughter Marlowe with ex Tom Sturridge.

And when it comes to her teenage daughter, Sienna said she's "got it all going on".

She added: "She's very cool. She says she likes bottom halves from me and top halves from Alexa - and she doesn't hold back with the criticism.

:"The other day, I put on this Chloé suede jacket - a really beautiful blue, gorgeous, cape-y thing - and she just went, 'Napoleoooon!'

"So I took it off. I do feel like I've got this great usurper in my midst…"