Sienna Miller. [Photo/Agencies]

Sienna Miller has taken up yoga to help with her pregnancy.

The 'Factory Girl' actress is currently expecting her first child with fiancé Tom Sturridge and has recently begun practicing the relaxation and strengthening technique because she hates working out.

She said: ''I have been trying to do some pregnancy yoga as I'm definitely not a gym person.

''My mum started up one of the first yoga schools in London in the 70s, so I should probably utilise her expertise as I have really bad posture. But I think I'd probably kill her if she tried to tell me to sit up straight.''

Sienna thinks her skin looks much better since she got pregnant - though she is unsure whether that is due to her having quit smoking and drinking alcohol.

She added to Marie Claire magazine: ''My skin definitely looks better since I became pregnant - although not smoking or drinking has probably helped with that.

''Body-wise I've been slathering on Dr. Hauschka Blackthorn Body Oil to try to prevent stretch marks, which is gorgeous and certainly seems to have worked so far.''