Mistral's kiss - Laurell K Hamilton

The time has come for Meredith Gentry to put aside her detective work and fulfill her ultimate obligation to the world of Faerie - where her efforts to conceive an heir to the throne of the Unseelie Court are crucial to restoring magic, and life itself, to the Fey kingdom.
And though her quest to produce an heir may be full of sensual pleasures, it is also fraught with peril: the shadows of intrigue stalk the royal court, and sabotage lurks at any turn. Merry's cousin schemes and plots, determined to see her fall. But, in the once-dead gardens of the world of faerie, something has re-awakened an all-powerful, malign magic. And Merry's own powers have turned wildly - dangerously - unpredictable. As plots and counterplots are hatched and strategies and subterfuges played out, the destiny of an entire world turns upon the fortunes of Merry Gentry: object of obsession, target of treachery and pawn of uncertain fate.