Ethan of Athos.

You'd think that an obstetrician on a planet forbidden to women would be underemployed...

Not so; Dr. Ethan Urquhart, Chief of Biology at the Severin District Reproduction Center, is one of the busiest men on the planet Athos. That is, until a mysterious genetic crisis threatens Athos with extinction.

Drafted to brave the wider universe for his cloistered fellows in quest of new ovarian tissue cultures, Ethan braces himself for his first encounter with those most alien of aliens...females of his own species. But braced or not, his wildest imaginings could never have stiffened him sufficiently for alliance with Dendarii Mercenary Commander Elli Quinn, an utterly gorgeous mercenary intelligence officer who has her own secret interest in Athos's problems...and Ethan as well.

The description comes from the publisher. This is one of the books in the Vorkosigan Saga.