How does having a baby represent hopefulness?

Hosseini sets up pregnancy as a symbol of hope throughout the novel. Mariam's pregnancies each offer her an opportunity to be hopeful for the future despite her bleak living situation. Laila's pregnancy with Aziza allows her to remain positive after she learns about Tariq's death. Aziza and Zalmai thus offer light and joy to a story that is otherwise bleak and dark. Childbirth is painful, and the pain that mothers feel during the various birthing scenes reminds us of the sacrifices that parents make in order to bring new life into the world. The mother’s pain is worth the joy and attachment that she feels once the child is born.

Additionally, the contrast between fertility and infertility has a traditional meaning: a woman's value in Afghan society has often been measured by her ability to bear children, specifically boys.