Oh, come now; if I suddenly acquired new sex-related complications on the order of being able to get pregnant, and I was also a new species, I'd probably want to avoid that for at least a while. The character doesn't know about what birth control may or may not be available, what STDs may or may not be rampant, what pregnancy and childbirth are like for cows, or what the sexual mores of the society she's in might be! And also has much more on her mind than figuring out how to get laid, let alone with species she's never considered fornicating with - and the pregnancy one would be from sex with a gender she's never been attracted to. "Yep, probably better not have any sex" is a perfectly reasonable reaction.
Not that she manages to hold on to it. I swear, there seems to be a rule that Human In Equestria fics end up involving sex with a native one way or another. Maybe it's a way for the human characters to become symbolically "married" to the nigh-utopian setting?
For the past two months, I've been writing, and posting, roughly two thousand words a day of "Myou've Gotta be Kidding Me", a story set in a "My Little Pony: Friendship is Magic" fanfic universe, "Chess Game of the Gods". Outside of the sheer NaNoWriMo-like exercise of pushing out near-daily chapters, I've also been trying to keep in mind the various principles I've learned from Yudkowsky and LessWrong, and to try to present them in a way that people who like reading MLP fanfics might be able to appreciate.
I've just come to something of a minor climax with chapter 60, and while I'll definitely be continuing the story, this seems like a good time to mention it here, for whatever feedback and constructive criticism anyone cares to offer.