Dividing the Sustain (Unabridged) [Unabridged Fiction‪]‬

In the future people will live for a very long time, but they must periodically "recast" themselves to maintain their sanity. They might change their sex, add another head, or re-engineer themselves to live in the upper atmosphere of Jupiter. In this wild romp set on a starship, a personality courier must uncover the secrets of a reclusive starship captain and his wife, who has been pregnant for three years.
Author James Patrick Kelly is a two-time winner of the Hugo Award and a 2007 Nebula Award winner. His stories appear frequently in Asimov's Science Fiction, and he writes the magazine's "On the Net" column. Publishers Weekly has called him "a meticulous craftsman in the demanding short-story form".