Thursday morning, 32-year-old Lauren Semanyk was taken away from the courthouse in handcuffs.
She did not speak to the media. The father, 34-year-old Joseph Milano, was already in jail on DUI charges.
Police say Semanyk and Milano tried to cover up the fact that their daughter Angelina got her hands on fentanyl-laced heroin and overdosed.
Investigators say they responded to the family home back in April for reports of a child going into cardiac arrest.
Police say the parents claimed the child drowned in a bathtub. She was pronounced dead at the hospital.
Arrest warrants were issued after the autopsy revealed the drug overdose.
"This is a very, very tragic story and it shows what drug addiction can do. The victim was a 10-month-old baby girl," said Upper Darby Police Superintendent Michael Chitwood.
"She was healthy and just learning to walk, she could say 'momma' and 'da-da'.... and she's dead," he continued.
Chitwood said the parents waited more than six hours before getting the child help, despite allegedly knowing the girl had ingested the drugs.