This is Stephanie Meyer's response which Ты can read on Twilight Lexicon: Several girls wanted to know if Edward would have a еще difficult time being around Bella when she?s having her period. Answer: Yes, a little bit, but he would never say anything about it?much too much of a gentleman. And Bella would be way to embarrassed to ask. (It?s not the same as a cut, though. It?s sort of "dead" blood, if Ты get my meaning).
OMG I KNOW!! that's been bugging me thru the ENTIRE series! i mean, what if she has a bitten cuticle или something, and there's a TIIIIINY bit of blood... that would count too, right? and sheesh... the period is such a huge thing to overlook. it kinda ruins the whole series, doesn't it? i mean there's no explaination and she's GOT to be having it (coz she was thinking about it in BD) so i guess it makes the whole series kind of a fluke... right?
well it doesnt mention it in the book because edward is to gentlemanly to mention it. and bella is to embarrased to ask. but the blood doesnt effect him has much a regular blood. because period blood is dead blood.