They decided abortion was a right and worked backward until they found a round hole in which to fit the square peg. Frankly I think it fits much better into the 13th amendment, but then that would also lead to the uncomfortable conclusion that parents may be compelled to involuntarily serve both unborn and born offspring, and I'm guessing they didn't like the implications that would have on child neglect laws.
The Roe case hinged on abortion being a right under privacy right. It was a very weak argument and even Ruth Bader Ginsberg (a very left leaning justice who died recently) didnt like that reasoning and thought it was weak: https://www.washingtonpost.com/history/2022/05/06/ruth-bader...