LONDON -  

The Duchess of Cambridge left a London hospital Thursday after being treated for acute morning sickness related to her pregnancy.

Clutching a small bouquet of yellow 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 with the couple's first child.

William visited his wife at the hospital every day, while media from around the world camped outside, seeking any news on the royal pregnancy.