Mum-to-be JENNIFER LOPEZ has pulled out of a performance at Sunday's (02Dec07) Movies Rock concert at the Kodak Theatre in Hollywood.The pregnant singer was initially scheduled to perform and present at the glitzy event, which is being held to celebrate music at the movies - but she's not taking any chances onstage.Her performance pull-out comes less than a month after Lopez and her husband Marc Anthony scrapped a rescheduled show from the end of their U.S. tour, citing scheduling conflicts.After months of speculation, Lopez confirmed her pregnancy last month (Oct07) after stage costumes failed to hide her growing baby bulge - and designer Roberto Cavalli let it slip that his muse's condition was causing him problems.Lopez was one of many performers, including Beyonce, Carrie Underwood, Chris Brown and Sir Elton John, billed to hit the stage at the Movies Rock event.