A recently born infant girl was found in a garbage bag on a back porch in a Brooklyn neighborhood, and the apparent mother and her two sisters were arrested, police said.

The baby was pronounced dead at a local hospital of asphyxiation and hypothermia, police said. The infant had been born alive, said Ellen Borakove, a spokeswoman for the city medical examiner's office

Laura Sergio, 25, who is believed to be the mother, was arrested Saturday and charged her with murder, police said.

Sergio's sister, 27-year-old Andria was arrested on a charge of improper disposal of a human body. Another sister, Cara, 29, was arrested on a charge of obstructing governmental administration.

Laura Sergio was taken to a hospital with a medical problem around 9 p.m. Friday, and a doctor called authorities to say she might have given birth, according to police.

Officers were directed to a Brooklyn home, where they found the infant unconscious around 3:30 a.m. Saturday.

A phone number for Laura Sergio at the address provided by authorities was non-published, and authorities said she was still hospitalized Saturday.