Norway's Crown Princess Mette-Marit has undergone a successful lung transplant and is recovering from the procedure, the royal household said in a statement on Wednesday. "We are delighted that everything has progressed well so far. In accordance with standard practice for all recent transplant recipients, Her Royal Highness the Crown Princess will remain admitted to Oslo University Hospital Rikshospitalet for several weeks to come," Are Holm, lung specialist at the hospital, said in the palace statement. Mette-Marit's condition, which causes scarring of the lungs, had deteriorated significantly over the past six months and her doctors announced on June 5 that the 52-year-old had been placed on the waiting list for a lung transplant.