Upper Darby police said the mother is a 15-year-old township resident.
She will be charged with recklessly endangering the welfare of a child. Her parents were unaware of the situation, police said.
The baby girl was released from the hospital Thursday and placed into the custody of Delaware County's Department of Human Services.
According to police, the hours-old newborn baby girl was left abandoned on Englewood Road Tuesday.
Resident Terrell Phillips said the baby was found wrapped in a little white blanket on a porch.
"I picked it up, and as I picked it up, the towel was unraveling, and I saw the baby still had the umbilical cord on it," Phillips said.
The baby was left on the porch of Phillips' neighbor, Tom Dailey, who was just getting home from work.
"He said, 'Mr. Tom, what is this?' And he says there's a baby here," Dailey said.
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