Norway’s Crown Princess Mette-Marit has been placed on a waiting list for a lung transplant after a further deterioration of her health, the royal household said in a statement on Friday.

The 52-year-old wife of Crown Prince Haakon, the heir to the Norwegian throne, was diagnosed with pulmonary fibrosis in 2018, a chronic disease that causes scarring in the lungs and leads to a reduced oxygen uptake.

“As a result of her life-threatening chronic lung disease and after thorough health examinations, her royal highness Crown Princess Mette-Marit has been placed on the lung transplant list,” the palace said.

Oslo University Hospital in December said the time was approaching when a transplant must be performed but that the crown princess had not yet been placed on Norway’s list of possible recipients.

Crown Prince Haakon, earlier this week, cut short an official visit to Japan, returning home to be with his wife. At the same time, the couple’s daughter, Princess Ingrid Alexandra, flew back to Oslo from Australia, where she is a student.

“She plans to come home soon. It has to do with the family situation. She wants to be with her mother,” Crown Prince Haakon, who has cut short an official visit to Japan due to the illness, said in a Tokyo press conference.

He said his daughter, who is second in line for the throne, “plans to complete her studies in Australia” but that he does not know how long she will stay at home.

The development of Mette-Marit’s lung disease was serious, and she will undergo a transplant “as soon as possible”, Oslo University Hospital Professor Are Holm said in a statement provided by the palace.

Prime minister Jonas Gahr Stoere has praised the crown princess for being open about her condition and has said this could help others suffering from similar problems.

The crown prince and princess are postponing the celebration of their 25th wedding anniversary, which was planned for August this year, the palace added.

Mette-Marit was 25, an unmarried single mother and a commoner when she met Haakon at a music festival in 1999, the beginning of an unlikely royal romance that started with a media furore and ended up winning over the bulk of the nation.