A 17-year-old Bronx mom has been charged with murdering her newborn son — who she threw out a window in October, authorities say. 

The teen tossed her day-old child out of her fifth-floor apartment window on East 158th Street on Oct. 24, police said. 

Police were initially called to Lincoln Medical Center around 3 p.m., when the teen told them she had previously given birth inside her apartment. 

Authorities searched the area and found the infant unconscious and unresponsive inside a flowerbed, cops said. 

He was pronounced dead at the scene by EMS. 

His death was ruled a homicide by the city Medical Examiner’s Effice. 

The young mother, whose name was not released, was arrested Thursday and charged with murder and manslaughter, cops said.