The remains were in a load of laundry that Spring Valley Hospital sent yesterday to the medical laundry company Angelica in nearby Henderson.
Henderson police spokeswoman Kathleen Richards says detectives determined it was an inadvertent mistake and it's not considered suspicious.
Hospital spokeswoman Gretchen Papez says a woman who suffered a miscarriage early in her pregnancy had arrived at the hospital by ambulance with the dead twins already wrapped in linens.
Papez says hospital officials are trying to determine how the mistake occurred.