In The Twilight world, male vampires have to mate with a human female to have a child. But that will end in tragedy for the human female's death, if the male vampire acts swiftly they can save both the child and mother.
Two vampires cannot have children. For example, the female vampire cannot carry a growing child, due to the fact that their bodies will no longer be able to gestate a baby to its full growth because of the fact that their bodies are frozen. They must either adopt children or turn a human at a proper age to do so - but this is against their law.