The Cullens and "that time of the month"

So, I was standing in my kitchen, making pizza rolls and, for some reason, thinking about Stephanie Meyer's Twilight series when a thought occurred to me. The Cullens get so crazy around the scent of blood that most of them find it hard to hold themselves back when Bella gets a little cut. Jasper is worse and probably would have eaten Bella if the other Cullens hadn't been there to stop him.

The high school the Cullens go to is filled with teenage girls and women. At the very least, all the teenage girls probably have their period once a month, and they probably don't all have it at the same time. The Cullens could probably avoid the girls who aren't in the same classes they are, but there's still a fair chance that, every single day, there is at least one girl in at least one of their classes who has her period.

Even assuming that Carlisle makes sure they can miss however many classes they need to in a day in order to avoid all these girls, the Cullen "teens" all use the cafeteria. Somewhere in that cafeteria, there is likely always a girl who's having her period.

It's possible that the Cullens (except for Jasper) just have really good control, but wasn't there a part in the book where Edward didn't go to science class one day because they were going to be looking at blood? If that was going to bother him, how could all those menstruating girls not?

Also, what did Edward do whenever Bella had her period? Did he avoid her for a week every month? How did poor Bella not die of sadness?

These are the weird thoughts that just pop into my head sometimes. And, since my timer just beeped, now I'm going to go eat pizza rolls.