Here's a fun assignment. Think of all of things you can do with yourself, then ask, do I have a constitutional right to do this? If it's not explicitly mentioned in the Constitution in unambiguous language, like the second amendment's unequivocal guarantee of your individual and unrestricted right to pack heat, then no, you don't have a right to it. The second part was kind of a joke. The first part not–you'll find that you have no explicit constitutional right to do most of the things you do. So the fact that something you do or can do is not explicitly mentioned in the constitution does not ipso facto mean it's not a guaranteed right. Or so I would think. Not so much George Will.
In Roe, the court said that the 14th Amendment guarantee of "due process" implies a general right of privacy, within which lurks a hitherto unnoticed abortion right that, although it is "fundamental," the Framers never mentioned. And this right somehow contains the trimester scheme of abortion regulations.
Since 1973 the court has been entangled in the legislative function of adumbrating an abortion code the details of which are, Wilkinson says, "not even remotely suggested by the text or history of the 14th Amendment." Parental consent? Spousal consent? Spousal notification? Parental notification? Waiting periods? Lack of funding for nontherapeutic abortions? Partial-birth abortion procedures? Zoning ordinances that exclude abortion facilities? The court has tried to tickle answers for these and other policy questions from the Constitution.
Last thing first. According to the Constitution, it's the judiciary's job to interpret the law. The Supreme Court interprets all laws in virtue of their consistency with the U.S. Constitution. That's its job. Second, did you think of any of the things you do which aren't explicitly mentioned as rights?