I have to tell my child since she was donor conceived.
Just a brief anecdote: I met a woman in my synagogue with three kids and the youngest (?age 7) looks at me and says "I was frozen" I must have look confused so the mother clarified. So I just replied indicating to my daughter - "she was too."

(wasn't quite sure how to respond otherwise.)
If you are worried about privacy you can just explain IVF without going into the "why" and share the why when they are older. But I agree that easiest if it is told as part of the birth story.