If you're in the market for a good story-time read, I recommend My Beautiful Mommy, a heartwarming tale of personal growth and breast augmentation by plastic surgeon Michael Salzhauer. The book is aimed at helping kids understand that even mommies can be insecure. See, even adults love instant gratification; but for them, face lifts work better than candy.
The author, who has four children of his own, explained that he sees kids of his patients come in with puzzled looks and ask if their mommy is dying. The book is meant to reassure children that the only party of mother that's dying is her soul.
A Park Avenue plastic surgeon recommends not telling younger children that their birth, and the correlated stretch marks, is what necessitated the tummy tuck. But we say go for it! In these godless times, kids need some sense of original sin.