Maya is raped when she is eight years old—that's about as messed up as sex and sexuality can get. And from the moment she's abused, her sexual identity comes into question. She confuses sex with love, she feels torn between womanhood and girlhood, and she doesn't know which way is up. Sex is only for bad people, right? Or married people? Or perverts? Throughout the course of I Know Why the Caged Bird Sings, Maya works her way through an understanding of sex. In the end, even if she's a bit misguided in her actions, she takes charge of her sexual identity.
In Caged Bird, sexuality of any kind is a bad and dirty thing. It only leads to pain, and it's best to stay away from it.
By showing her the beauty that can come from sex, Maya's baby helps her heal from her sexual abuse as a child.