Well, duh, of course. It can't regulate abortions because having one (including a partial-birth abortion of course) is a constitutional right (Amdt. XIV - penumbra).
Prior to R. v. W., the several states through their sovereign power expressed by their legislatures regulated abortion. It was legal in California and New York, banned in Texas and Massachusetts. That's how the constitution works, how it worked for almost 200 years. The New Deal greatly eroded the Constitution, the assault started with Lincoln and the Civil War.
Frankly, I think the 14th amendment comes closer to banning abortion than any penumbra comes to legalizing it. Conservatives never pressed for the Court to ban abortion in states allowing it, although they had (have) a better case.
Thank you. This causes me to ask an additional question; how does a moral wrong become a civil right? To ask it a different way, what in the Constitution causes abortion to be the business of the Federal Government?