This has started bouncing around the Twittersphere already, so I take no credit for it. But it bears repeating.
Vampires. Dead, right? We’re agreed on that. If they’re dead, then there’s no heartbeat. No heartbeat, no blood pressure. And as Twilight vamps shatter like glass when killed, we can assume that they are effectively bloodless.
Without blood pressure, how then does Edward get an erection with which to impregnate his blushing bride? Unless the process has gifted him with what no less a thinker than William Gibson has already described as:
A discussion to be had along the lines of that which takes place whenever we consider the possibility of Superman and Lois Lane starting a family. Enquiring minds wish to know.