The 30-year-old actress, who is currently expecting her first child with fiance Tom Sturridge, says her skin is much improved since she fell pregnant, Contactmusic reported.
"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," she said.
Miller says she is unsure whether her skin looks good due to her having quit smoking and drinking alcohol.
"My skin definitely looks better since I became pregnant although not smoking or drinking has probably helped with that."