My Sister's Keeper: Jodi Picoult

Then the test results come back time and again to show that no one in their family is a match for Kate. If they are to find a donor for the crucial bone marrow transplant she needs, there is only one option: creating another baby, specifically designed to save her sister. For Sara, it seems the ideal solution. Not only does Kate live, but she gets a beautiful new daughter, Anna, too.
Until the moment Anna hands Sara the papers that will rock her whole world. Because, aged thirteen, Anna has decided that she doesn't want to help Kate live any more. She is suing her parents for the rights to her own body.