The Alfie star is expecting her first child with her boyfriend, actor Tom Sturridge, this summer (12) and she is doing all she can to prepare for the birth.
She tells Marie Claire magazine, ""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.""
Miller also admits she has noticed upsides to carrying a baby, adding: ""My skin definitely looks better since I became pregnant - although not smoking or drinking has probably helped with that.""