While I can appreciate the female genitalia as a fascinating and beautiful thing, the thought of it covered in blood makes me think of castration. (Or an inconveninetly placed wound)
I can't help my male-centric view of sex. If I ever were to have sex with a woman though, I'd rather they weren't menstruating. Then again to me the idea of sex with a woman seems unfair since I can't rightly appreciate their beauty in a sexual way.
Which brings me to the question of why I posted a reply in the first place.