The Duchess of Cambridge left a London hospital Thursday after being treated for acute morning sickness related to her pregnancy. Clutching a bouquet of roses, the former Kate Middleton smiled and posed briefly for a photograph alongside her husband, Prince William, before leaving King Edward VII Hospital. She stepped delicately into a waiting car. The couple’s office said she would head to Kensington Palace in London for a period of rest. She had been in the hospital since Monday. Officials from St. James’s Palace have said the duchess is not yet 12 weeks pregnant. Royal officials announced the pregnancy Monday, their hand forced by the duchess’s admission into the hospital.