Priscilla Caldera, 18, of Phoenix, was arrested Tuesday, according to Maricopa County Sheriff’s Office online booking records.
Members of the Phoenix Police Department said they found blue oval pills inside the boy’s crib, according to KNXV.
The boy’s grandmother told police she placed the boy and his twin brother in their crib and left the room for a few minutes before returning to check on them, KNXV reported.