She is a pin-up for size zero wannabees everywhere, but Simple Life star Nicole Richie, showed off an impressive baby bump out and about in Hollywood yesterday.

Wearing a stretchy grey sweater and sensible flats, Nicole was accompanied by her fiance, Good Charlotte frontman Joel Madden.

Well-wishers will be relieved to see the 26-year-old daughter of singer Lionel Richie has put on weight for her pregnancy. The troubled star had suffered a slide into drugs and driving related offences last year, which saw her spend a short time in prison.

Nicole Richie is engaged to rock star Joel Madden

Nicole recently revealed her baby had saved her life. "I owe this baby everything and I have a responsibility now," she told Diane Sawyer on ABC News.

"Besides being responsible for myself, I'm now responsible for someone else. And I have to set the right examples. I have to really be someone that I would want my child to look up to."

However, the socialite admitted she could not believe she was pregnant at first. She told Access Hollywood: "I didn't believe it. I was in shock. I took about 5 different tests!"