Yes, I feel for the baby. However, I place a large percentage of the blame on the young woman's parents. How does a grown woman not have language? You all saw Genie in your Psychology class in high school or college. It's called language deprivation. Without language one can (and does) become brain damaged. A thorough cognitive and psychiatric eval needs to be done on this woman. Then, if she is shown to understand what she has done, punish her. Regardless, her parents are guilty of child abuse and neglect in my book.

Just last week we all expressed outrage at the family who denied their children food. This family denied their child language, and interaction with humans on a meaningful level. They denied her an education. Before you argue, think for a moment how much you would learn about... well, everything if you were not given linguistic access to it. I taught deaf kids for many years (and teach deaf adults now). It happens all the time. Sadly.
Its a fully preventable form of child abuse. Deaf kids can learn anything. If they have access to it.

Is it tragic for the baby? Absolutely. But let's see what the young woman's cognitive capabilities are before we decide prison is best for her.