Kate Middleton is still on maternity leave following the birth of her daughter Princess Charlotte earlier this month, but even though it will be a few weeks before the Duchess of Cambridge returns to her royal duties, the 33-year old is still thinking of others as she recently wrote a heartfelt letter on behalf of children who are suffering from life-limiting illnesses.

The letter, which was sent from Kensington Palace, and released by the charity Together for Short Lives, explains the importance of Children's Hospice Week, which launched on Monday, May 11 and runs through Sunday, May 17.

"For families of children with life-limiting conditions, every moment is precious and every memory needs to be cherished and celebrated," wrote the Duchess. "Children's hospices strive to create happy moments in the most difficult times any family could face. I hope you will join me in supporting Children's Hospice Week and work to make every moment count for all families."

Children's Hospice Week is a fund and awareness raising venture to help make sure that parents of children with life-limiting conditions have the support they need to make the most of every minute they have with their children. In the United Kingdom, it has been reported that there are 49,000 children living with life-limiting conditions.

Supporting Children's Hospice Week has become something that the Duchess contributes to in one form or another annually and it's an area in which she is said to be eager to work further later this year. The Duchess is a patron of East Anglia Children's Hospices (EACH), and last November, she was moved to tears after meeting and talking to a mother whose child has been cared for at one of the EACH hospices before passing away.

Together for Short Lives is urging people to support the week by sharing a memorable moment on social media using the hashtag #momentscount.