Police say paramedics were called to a home on Doris Lane Tuesday.
A five-week-old baby was rushed to a Birmingham hospital where she's listed in critical condition.
Investigators say the baby's uncle told them he tried to stop the child from crying by putting his hand over her mouth. But, when the little girl's eyes rolled back in her head, he called 911.
The teenager was arrested for assault, but police say that charge could be up-graded if the infant dies.