The pregnant wife of Britain's Prince William has left a hospital in central London after four days of treatment for severe morning sickness.

William and his wife, Catherine — known formally as the Duke and Duchess of Cambridge — emerged from London's King Edward VII Hospital Thursday. St. James Palace has announced that the royal couple will stay at their London residence while Catherine continues to recuperate.

On Wednesday, a pair of Australian radio hosts called the hospital, pretending to be members of the royal family. They tricked a nurse into giving them private information about Catherine's condition, which caused a public outcry. The Sydney radio station has apologized for its actions and the hospital has launched an investigation into the breach of security.

St. James Palace announced on Monday that the royal couple are expecting, after the 30-year-old Catherine was admitted to the hospital. William, who is second in line to the throne after Prince Charles, married the former Kate Middleton in April 2011, in a Westminster Abbey ceremony that drew a worldwide audience of some 2 billion. Their first child will be third in the line of succession.