She's one of the most privacy-conscious stars, but she's clearly happy to bare all in the name of art.
Sienna Miller might have kept most of the details of her first pregnancy under wraps but now her pregnant body is out there for the world to see.
The 30-year-old star decided to take the plunge a la Demi Moore and show off her baby bump in a portrait by acclaimed artist Jonathan Yeo
In July, just weeks before the birth of her daughter Marlowe, the actress decided to sit for the British artist for a series of portraits which are due to be exhibited in (I’ve Got You) Under My Skin at the Circle Culture Gallery in Berlin.
Showing off her completely naked body, the life-like portrait of the Alfie actress is painted in gold and shows the star with her hands on her arched back, pushing out her prominent bump.
Just like stars including Demi, Jerry Hall and Kate Moss, Sienna has chosen to show the world her pregnant body in all its glory.The blonde actress met the high profile contemporary artist, who's painted the likes of Tony Blair, Nicole Kidman and Prince Phillip, eight years ago in Los Angeles.
The pair struck up a friendship and since then the star has posed for a series of portraits for him.
Jonathan's striking portrait, which is shown alongside paintings of plastic surgery, was created to confront society's reactions to the naked female form.
'I wanted an image that epitomised the human body in its most naturally beautiful state to make the sharpest possible contrast with my other paintings in this exhibition, which document patients undergoing cosmetic surgery in a bid to help them conform to societal notions of beauty,' Jonathan writes in the exhibition catalogue.
'It has been 22 years since a pregnant Demi Moore caused uproar by posing for Annie Leibovitz on the cover of Vanity Fair. In that time society has become almost completely desensitised to the daily exposure to people who have surgically distorted their appearance for artificial reasons,' he continues.
'Yet certain sections of society are still uncomfortable with the appearance of pregnancy and images of naked expectant mothers are rarely seen.'
The artist admits that Sienna was the obvious choice to showcase what natural beauty really is: 'The power of the painting partly lies in the fact that Sienna is widely regarded as being one of the most naturally beautiful actresses in the world as well as being a fashion icon to a generation of girls.
'It is a tribute to her courage and self-confidence that she agreed to sit for this.'