Protecting the Dignity of Unborn Children Act of 2018 This bill amends the federal criminal code to make it a crime to recklessly dispose of or abandon fetal remains in a landfill or in any navigable waters of the United States. The term "fetal remains" means any part (except a cremated part) of a deceased human fetus following an abortion. A violator is subject to a fine, up to three years in prison, or both.