The Princess of Wales delayed her cancer announcement in order to tell her children at a time that was “right for them”.
In a video message to the nation, Kate said it had “taken us time” to explain the news to her children George, 10, Charlotte, eight, and Louis, five, “in a way that was appropriate for them”.
Kensington Palace said Kate wanted to share the information when she and her husband the Prince of Wales “felt it was right for them as a family”.
It is understood the family wanted to put her health and their children first before making the announcement.
Kate was pictured with her children in a photograph posted on social media on Mother’s Day, which was said to have been taken by William.
The photograph was later withdrawn with a “Kill” notice by international picture agencies hours later because of suspicions it had been digitally altered.
In her video message, Kate said: “It has taken me time to recover from major surgery in order to start my treatment.
“But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK.
“As I have said to them; I am well and getting stronger every day by focusing on the things that will help me heal; in my mind, body and spirits.”
It is understood Kate wanted her children to understand the news before it became public knowledge and that they have been her priority throughout.
The update was said to have been shared now the children are away from school on their Easter holidays.
The news followed huge speculation on social media over the past few days about an impending royal announcement.
It also follows reports of a staff member at the London Clinic, where Kate underwent major abdominal surgery in January, allegedly attempting to access her private medical records.