This is an interesting tale but unusual for the fact that it doesn't read much like Fitzgerald. The prose style is a bit melodramatic and pulpy. It's fun to read, but not what you might expect if you've read other Fitzgerald stories. It reads as if he was trying to dumb it down. However, still a bit poignant in places.
The story reminded me of a classic by Ballard called Mr F is Mr F - which I think is a better story. In Ballard's version, a man grows backwards, but even beyond regressing to become a a baby, he ends up back in the womb, of his wife!