Vampires - Can't have kids

Arra glanced at me archly and said, "Women do not make good vampires. The entire clan's barren, so the life doesn't appeal to many of us."

"Barren?" I inquired.

"We can't have children," she said.

"What— none of you?"

"It's something to do with our blood," Kurda said. "No vampire can sire or bear a child. The only way we can add to our ranks is by blooding humans."

***

Cirque Du Freak: Vampire Mountain, Chapter 16