Milwaukee police said they've arrested a mother in the death of her six-week-old infant.

Investigators said the 30-year-old mother was believed to be under the influence of narcotics when she fell asleep on a couch with the baby and slouched down onto the child causing the infant to lose consciousness Saturday night.

Authorities said the baby died at Children's Hospital on Monday. The Milwaukee County Medical Examiner said an autopsy will be conducted Wednesday.

Police will refer the case to the Milwaukee County District Attorney's Office for possible charges.