“The question they ask is, are you going to die?” she said. “You yourself don’t know the answer.” With the new papers, she said, comes a charge to doctors and other health care professionals to help parents frame the answer to that difficult question, and not to delegate it to others. “There’s no easy way but I think it’s really important we do it and important that professionals navigate those really difficult waters, and hold our hand through the journey.”

The guidelines take into account the ways that children’s understanding of death and dying changes as they grow, and give advice for how to shape these conversations. With very young children, Dr. Stein said, discussion early on might emphasize the seriousness of the condition and the importance of treatment, but not necessarily the issue of death, unless they ask.

Children around 5 to 7 often feel very responsible when bad things happen, Dr. Stein said. One 7-year-old boy whose mother died became convinced that it was his fault because she had missed a clinic visit one day when he had a bad tantrum. “He felt he had caused his mother’s death, because she hadn’t gone to the clinic and gotten the information she needed,” Dr. Stein said.

When the children are the patients, they also worry that these conversations will be too painful for their parents, said Dr. Emily Harrop, a consultant in pediatric palliative care at Oxford who is a co-author on the articles. “I have seen in practice children becoming quite anxious and distressed, feeling a protectiveness of their parents, not wanting to open the conversation, perhaps not even feeling they have permission to die.”

She recalled caring for a 4-year-old girl with a brain tumor whose mother believed that her daughter did not know she was going to die. When the mother was out of the room, the child asked the doctor, “How will I get through the ceiling when I go up to heaven?”

In her experience, Dr. Harrop said, “Children who’ve had good information sharing are much calmer, less anxious.” That requires having the conversations well and carefully, and keeping them free of jargon. “I would always start the conversation by having the child say to me what they understand, so I understand how they have received information,” she said.

Dr. Kelly described her own medical team as “exemplary” in how they broke the news to her, but at the moment of diagnosis their focus was entirely on her, while she was more anguished about her children. “It would help tremendously if these conversations start with health care providers,” she said.