LONDON (AP) — Prince William and his wife, Kate, marked the 9th birthday of their daughter Charlotte on Thursday by posting a picture of her smiling for the camera as she posed near a plant with pink flowers.

The photo, taken by Kate, the Princess of Wales, was posted on X, accompanied by the words “Happy 9th Birthday, Princess Charlotte!” and a cake emoji.

Kate has tried to ensure that her three children have as much stability as possible as she undergoes treatment for an undisclosed form of cancer. She has stepped away from public duties since undergoing abdominal surgery in January.

In announcing her cancer diagnosis to the nation, Kate said she and William “have been doing everything we can to process and manage this privately for the sake of our young family.''