Who is Sarah Fitzgerald in My Sister's Keeper by Jodi Picoult?

Sarah Fitzgerald is Kate and Anna's mother. Her life is centered around her daughter Kate's illness and in desperation, she has another child (Anna) in the hopes that Anna can be a donor to ultimately save her sister's life. Sarah is devastated by Anna's refusal to donate her kidney and angered by the case she brings before the court. In the end, Sarah comes to understand that her feelings and desires should never have trumped those of her girls.