"Spending quality time together is such an important aspect of family life, but for those caring for children with life limiting conditions, even this simple act can prove to be incredibly challenging," she wrote in a message to mark Children's Hospice Week.
"The practical realities of providing round-the-clock care mean even activities that so many of us take for granted can be just too complicated."
In her role as royal patron of East Anglia’s Children’s Hospices (EACH) the Duchess praised the "amazing, and life changing support" offered by hospices and palliative care providers, which provide a "lifeline" to parents and children.
"This support gives these families the space they need to simply spend time together, which is so important in the most difficult times imaginable," she added.
Children's Hospice Week runs from 23 to 29 May with the aim of raising awareness of children with life-shortening conditions and the work hospices and palliative care providers do to support families.
In March, the Duchess attended the opening of a new shop raising funds for EACH, a charity that cares for children with life-threatening conditions across Cambridgeshire, Essex, Norfolk and Suffolk.