The girl is heavyset and was still having periods during the pregnancy. She gave birth to a baby boy at a home on Edinborough Road on the city's west side.
The baby and girl were taken to a local hospital.
A family member told police the teen had a sexual relationship with a teen boy, but the girl's mother and siblings were unaware of it.
Police are investigating the relationship between the teens and the household dynamics to determine if there was any abuse or neglect.
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