The natural consequence of defining fetuses as "persons" is to charge pregnant drug addicts with murder.

Such charges will not protect anyone from being harmed. Quite the contrary: they drive pregnant drug addicts away from medical treatment because they fear it will lead to prosecution.

A potential person that never begins to exist cannot suffer any wrong or harm. Thus, the idea of "murdering" a fetus is an absurdity; that is simply a form of abortion. Even if the abortion doesn't follow the usual rules, it isn't murder.