No legislation needed, because the amendments are self-executing.
1. A “Fetus” is a Life and a Person
1.1. We start with the proposition that the fetus is a life and therefore a person, both biologically and colloquially. I’ll skip the biological for which there is vast material readers can find for themselves. Instead I’ll rest on the colloquial argument: as Ann Coulter once said, no one gives “a fetal shower” or says “My fetus is due next May”, or “My fetus’s tiny legs are kicking my ribs.”
1.2. I have assumed that, despite the claims of some, the 14th Amendment is actually valid.
2. Pertinent Federal Constitutional Provisions
2.1. Amendment 5: Federal Due Process: “No person . . . shall be deprived of life, liberty, or property, without due process of law . . . .”
2.2. Amendment 9: Unenumerated Rights: “The enumeration in the Constitution, of certain rights, shall not be construed to deny or disparage others retained by the people.”
2.3. Declaration of Independence: Rights to Life, Liberty, and Property; Government’s Duties to Secure Those Rights: “. . . We hold these truths to be self-evident, that all men are created equal, that they are endowed by their Creator with certain unalienable Rights, that among these are Life, Liberty and the pursuit of Happiness. That to secure these rights, Governments are instituted among Men, deriving their just powers from the consent of the governed . . . . 
2.4. Amendment 14, §1: Protections of persons from unlawful state action. “[N]or shall any State deprive any person of life, liberty, or property, without due process of law; nor deny to any person within its jurisdiction the equal protection of the laws.”
3. Reasoning and Conclusions
A. State Locale Cases
3.1. By state locales, we mean all real property in the United States which is not federal property.
3.2. Elective abortions are barred by the 14th Amendment Due Process Clause (applicable only to states). The 14th says in part, “[N]or shall any State deprive any person of life, liberty, or property, without due process of law.” That clause overrides any and all state laws that permit elective abortions.
3.3. Due process normally applies to require a judicial hearing before a criminal defendant can be executed, imprisoned, or fined; for due process requires notice, a judicial hearing for one whose life, liberty, or property is imperiled, and also a fair opportunity to be heard. 
3.4 But the provision for a judicial hearing in elective abortion cases is perhaps impossibly unworkable, for the person to be executed would always be an innocent child. Consequently, unborn life can be never be taken by elective abortion, for due process can never be given to an unborn child; and therefore the Due Process Clause stands as an absolute prohibition against elective abortions.
3.5. But what about non-elective abortion cases? In those cases, one might ask “What about the life of the innocent mother? What about her life in cases where continuing the pregnancy would endanger her life?
3.6. According to Dr. Ron Paul, an obstetrician who has delivered more than 4000 babies, the cases where the mother’s life is actually in danger are practically nil. “In delivering nearly 4,000 babies, I personally never came across a need even to entertain the thought of therapeutic abortion for the health of the mother . . . .” 
3.7. But taking the rare case, we encounter profound legal, moral, and medical issues. Two innocent lives; which one is to be deliberately killed? One could suppose that the mother’s right to self-defense (even against her own innocent child who is killing her) would decide the question in her favor.
3.8. I put that question aside for another discussion and concentrate only on the vast majority of cases where the abortions are elective and continue next with another applicable and probably more pertinent part of the Constitution.
3.9. There is another and more direct 14th Amendment ground upon which denies the right to elective abortion: “[no state may] deny to any person within its jurisdiction the equal protection of the laws.”
3.10. At the time the 14th was adopted, blacks were being regularly brutalized by gangs of thugs and killed by lynch mobs. Their properties were being destroyed. The abysmal failure of the South to protect blacks was an American disgrace that needed to be quickly remedied. The remedy the 14th Amendment framers devised was the Equal Protection Clause, which, by its terms, required states to protect blacks by enforcing laws against mayhem, murder, and so on.
3.11. Professor Raoul Berger makes that point well:
What then is the substantive content of the words “equal protection of the laws”? The almost exclusive focus on “equal” has obscured the significance of the word “protection.” Yet it is “protection” that is the subject of discourse; “equal” is the modifier. Whatever “protection” is furnished must be “equal.” What, it needs to be asked, was to be protected? The abysmal failure of the South to protect the “person and property” of blacks against violence and murder, to safeguard the means whereby they could exist, furnishes the answer. That approach can rescue analysis from treating the word “equal” as if it were a crystal ball. “Protection,” if given, must be impartial.
3.12. The problem “equal protection” addressed was how to guarantee that every person, citizen or otherwise, within a state was entitled to the same law enforcement protection, and the immediate effect was that blacks could legally insist, for example, on the same police protection as whites.
3.13. The same “equal protection” rationale applies to unborn persons: states must guarantee the same police protection to unborn babies as it does for all other persons. Consequently, just as states were constitutionally-bound to protect blacks from violence, states have the constitutional duty to protect the unborn. States could start by shutting down all the abortion mills present in the state without further ado.
3.14. Conclusion: In state locales, elective abortions violate the 14th Amendment Due Process and Equal Protection Clauses.
B. Federal Locale Cases
4.1. Federal locale cases include cases arising in federal enclaves: the District of Columbia, federal properties, and federal territories.
4.2. The 5th Amendment Due Process Clause (which applies only to the federal government, but which is almost identical to the 14th Amendment Due Process discussed above) says, “No person shall be deprived of life, liberty, or property, without due process of law . . . .”
Therefore the conclusion in paragraph 3.4. above also applies to federal properties: Save for the rare case of an endangered mother, no unborn life can be ever be taken, for due process can never be given to an unborn child; and therefore the Due Process Clause stands as an absolute prohibition against elective abortions.
4.3. Unlike the 14th Amendment, the 5th Amendment does not have an Equal Protection Clause. However, the 9th Amendment (which binds only the federal government) is undergirded by the Declaration of Independence’s proclamations that “all men are created equal” and “to secure these rights, Governments are instituted among Men”. That provision in effect supplies a federal equal protection guarantee for the born and unborn. Both must be protected against murder and mayhem.
4.4. Conclusion: In federal locale cases, elective abortions are prohibited by the 5th and 9th Amendments.
See also Amendment 8 prohibiting cruel and unusual punishments.
1] Found in the United States Statutes at Large, p.1 @ http://memory.loc.gov/cgi-bin/ampage?collId=llsl&fileName=001/llsl001.db&recNum=124
 “The fundamental requisite of due process of law is the opportunity to be heard. Louisville & N. R. Co. v. Schmidt, 177 U.S. 230, 236; Simon v. Craft, 182 U.S. 427, 436. And it is to this end, of course, that summons or equivalent notice is employed. Grannis v. Ordean, 234 U.S. 385, 394 (1914) @ http://supreme.justia.com/us/234/385/case.html
 The Fourteenth Amendment and the Bill of Rights, pp. 122-123.
 See, for example, Yick Wo v. Hopkins, 118 U.S. 356 (1886) (unequal administration of law) @ http://laws.findlaw.com/us/118/356.html
See also blog: “Roe v. Wade: Heroes and Villains” @ http://constitutionalboe.com/uncategorized/roe-v-wade-villains-and-heroes/