Police said the teen had thrown the baby out of the window of a building on St. Lawrence Avenue.
The mother is being interviewed by detectives.
An autopsy by the medical examiner will determine if the child was born alive, according to police.
Police said a newborn girl was found in the courtyard of an apartment building around 11:15 a.m. on Wednesday.
The child was discovered by a building worker. She was unconscious and unresponsive with the umbilical cord still attached.
The contractor then notified the building superintendent, who told Eyewitness News that he wish he had known sooner.
"I was like crazy because they say the baby was there for almost three or four days and the baby was next to my living room," said the building superintendent named Carlos. "I could have literally looked out the window and saw the baby."
EMS pronounced her dead at the scene and the Medical Examiner will determine her cause of death.
Residents said they are in shock.
"Why not take the baby to church, you don't want the baby, take it to church or for somebody to come take care of the baby," one resident said.
The law allows a parent to drop a baby at a hospital or staffed police or fire station without having to give a name.
According to police sources, officers believe the teenage girl was hiding that she was pregnant. They also said the area where the baby was found is apparently hard to get to.
So far no arrests have been made.
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