What evidence, cognitive data, phenomena, or empirical observations lead to such a conclusion (that a human fetus has no value or sacred character)? Is there any basis in reality for such a conclusion? Indeed, for such a conclusion to be a guiding principle of government policy?
Being a negative claim, it doesn't call for a basis. Absence of value doesn't require justification. Values are applied only to things which we initially have no value for. Justifications are applied to things we initially have no justification for. By default we are unthinking creatures who do not value or justify things, even many of the things we are privy to. Burden of proof is placed upon the claimant. If you value something, and wish others to share your values, you need to persuade them.