A 32-year-old South Jersey woman pleaded guilty Thursday to aggravated manslaughter in the January death of her 7-month-old baby.

Lisa Scalia, of Ventnor, admitted she was high on drugs when she administered a fatal dose of methadone to her daughter.

On Jan. 3, Ventnor police and first responders found the baby unresponsive in the family's home. The child was first transported to the AtlantiCare Regional Medical Center, then transferred to St. Christopher's Hospital for Children in Philadelphia, where she died five days later.

It was initially believed that Scalia, who had heroin and oxycodone in her possession when police arrived, had rolled over onto her baby. Scalia was arrested and charged Jan. 4 with endangering the welfare of a child and four counts of possession of controlled substances.

After her daughter's death, the charges were upgraded to aggravated manslaughter.

The Medical Examiner's Office determined the baby died from "complications of methadone intoxication," the Atlantic County Prosecutor's Office said.

Under a plea deal, Scalia is to be sentenced to eight years in state prison. She must serve 85 percent of the sentence before becoming eligible for parole.