This book is the fourth is the Giver series by Lois Lowry. That said, you do not need to have read any of the previous books to enjoy this emotional dystopian novel (but you should, because they are all very good!).
The story starts in Claire’s community, where she had been assigned the task of Birthmother when she turned 12. Every child in this community is assigned a job at that age, and hers was to bring newchildren in to their world. After a birth gone awry, Claire is re-assigned to the fish hatchery, but thoughts about the baby she gave life to linger in her mind. The community assigns families to each other just like they assign jobs, so Claire would never have known her child, but she finds a way to spend time with him even though it is against the rules. After her small son is taken from the town by another young boy Claire goes on a perilous quest to escape the world she knows and find the only person she has ever loved.