Abortion, as an ideological issue, makes no sense. Is a fetus/embryo/whatever a human life? If so, then abortion is murder. If so, then abortion should not be legal. Thus, whether or not abortion should be permissible depends on when human life begins.
What is ideology? According to Phil Converse, who wrote the most cited article on public opinion, "The Nature of Belief Systems in Mass Publics," an ideology is a set of connections between issue positions. To be liberal is to hold a set of liberal positions across issues, and to be conservative is to hold conservative positions across issues. So, why the hell should one's belief about the propriety of economic redistribution have anything to do with one's belief about when human life begins?
Logically, it shouldn't, and that demonstrates one of Converse's most important points. Not all "constraints," in Converse's terminology, are logical constraints. Many are social constructions. For a variety of reasons, we have socially constructed ideology such that liberalism means supporting redistribution and abortion rights and conservatism means opposing redistribution and opposing abortion.
Constitutionally, though, what is the basis for saying that abortion is a constitutional right? There's the rub. Those who identify as "liberal" also tend to say that they think the Constitution is a "living document!" It changes with the times and culture! Therefore, we must interpret it in different ways over time. So, no, the Constitution never mentions abortion, and the framers would have opposed it, but we are a different culture now!
Every supposed philosophy of constitutional interpretation will quickly collapse under the weight of its own bullshit if given any scrutiny, but that's not the point. The point today is the Texas fetal burial law. What's going on there?
How does one evaluate culture and thereby the "living document" of the Constitution? Well, if we, as a culture, are burying each fetus from an abortion or miscarriage, doesn't that say something about how we, as a culture, have come to view the beginning of life?
This is why such laws are constitutionally important. If they exist, their existence is evidence of cultural views on when life begins, and that is important for how we take the vitals on that "living document."
Note that such laws wouldn't carry constitutional weight for any other philosophy. Cultural standards don't matter to "strict constructionists," so you can't pull this crap on them!
This is a "live by the sword, die by the sword" type of thing. If rights are not fixed, then they can disappear as well as appear. That is the flip side of the "living document" philosophy. Of course, liberals would rather just pass a constitutional amendment stating a right to an abortion in plain text to avoid this kind of stuff, but that ain't gonna happen.
Incidentally, anybody check Ruth Bader Ginsberg's vitals lately? I find it fascinating how much liberals still love her even though she was too stupid and arrogant to step down when it would have been a lock for Obama to replace her. The odds of her living through four years? Low. Maybe she could get through two and hope for the Democrats to retake the Senate in 2018, with Schumer blockading the Supreme Court the way McConnell did, but the Democrats probably don't have the balls for that. Face it, liberals. Ginsberg was an arrogant fool for not stepping down when Obama could have named a successor. Just an aside...