The states can not define human life. The federal government has already defined it.
1 U.S. Code paragraph 8 -"Person", "human being","child", and "individual" as including born-alive infant.
(c) Nothing this section shall be construed to affirm, deny, expand, or contract any legal status or legal right applicable to any member of the species homo sapiens at any point prior to being "born alive" as defined in this section
According to Alec Walen in "The Constitutionality of States Extending Personhood to the Unborn" , University of Minnesota Law School Scholarship Repository, 2005;(
https://scholarship.law.umn.edu/cgi/viewcontent.cgi?article=1062&context=concomm) states can restrict abortion when they have a compelling interest in the life of the fetus because there is no "firm ground" in Roe for prohibiting states from taking a compelling interest in the fetus.
Walen says that "if states were to treat unborn humans as persons in the whole sense (or close enough to the whole sense), then those states should be permitted to take a compelling interest in the lives of (pre-viable) unborn humans. And if they were to use that interest to shape and limit the right to an abortion, they would be acting just as states that prohibit abortion on post-viable fetuses already act under Roe.
But, says Walen, states can't just say they have a compelling interest, they must be demonstrated to show that the the life of unborn humans is a primary concern of the state or the laws restricting abortion are invalid.
In conclusion Walen says, "The problem for Roe is that the doctrinal footing rests on two feet. One foot is the claim that a woman has a fundamental liberty interest in choosing whether to bear a child. That foot is still strong. But the other foot is the claim that states do not have a compelling interest in the lives of unborn humans." ....... "Roe is vulnerable to a motion for reconsideration if and when states can demonstrate that they treat, or come sufficiently close to treating, the unborn, at some stage prior to viability, as persons more or less "in the whole sense. If Roe is reconsidered in this light, then any constitutional protection for abortion rights would have to be framed so that those rights are well grounded even if states do have, and do take, a compelling interest in the lives of unborn humans, even prior to viability."
My comment: Since the health of the fetus is inextricably linked to the health of the mother the only way a state could demonstrate their compelling interest in the health and welfare of the fetus would be to design, fund and implement pre and post natal nutritional, medical, financial and mental health support programs for women. Those states so desperate to punish women by banning women have never shown the slightest interest in spending any money to help women, especially not poor women live lives that support a healthy baby.