Werewolves have a harder time working with their genetics to produce children among their own. Due to the infecting dual-nature of their Lycanthropy, they are limited to only one genetic combination that can be successfully carried by the females.
Female werewolves have come to a sort of natural compromise with the genetics of their feral side. When supplies are in abundance and the climate is suitable, a female werewolf becomes available for pregnancy four times a year. The window is narrow, a day at most.
Females can still shift to wolf form during most of the pregnancy, but as they get further along, it becomes more and more difficult and can pose more problems. Shifting during the last two weeks is almost always a problem, and shifting during labor or giving labor while in wolf form will result in catastrophe. Many females will end up inducing labor to prevent the pregnancy from ending near their phase.
Shifting to the berserk form, Fireblooded, is guaranteed to end the pregnancy. Because hormones cause emotions and tempers to run high, this can be a problem for many Vitra females.
If a female can successfully carry the born werewolf child to term and give birth to it, however, it has a stronger chance of making it to adulthood than regular children. Born werewolf children start with higher body temperatures, giving them a small fraction of the "healing factor" and disease resistance that werewolves have once they have fully come into their powers.