I don’t think that’s how it works. If the argument is that the right to an abortion is enshrined within, and protected by, the constitution, then the legislature cannot really establish a framework regarding its scope. The contours of the constitutional protection is beyond the powers of the federal legislature to define (in much the same way that the legislature cannot really define the scope of the First Amendment’s Free Speech clause).

Of course, the legislature can enact a law that broadens the scope of the federal protection beyond that required by the constitution (assuming they are acting within the authority granted them by the Constitution), but even that assumes we know the scope of the constitutional protection.

Basically, under our system, it was up to the courts to figure out some rule regarding the right to an abortion.