It wasn't the first time a vampire impregnated a human, as shown by the half-human/half-vampire South American native that appears at the end. However, the Cullens knew nothing about his existence until that time, nor could they assume the fetus was fully vampire. They therefore had no idea how to treat Bella's pregnancy.
Chosen answer: It was the first time that a vampire ever got a human pregnant, and they didn't know what will happen.
Anastasios Anastasatos
It wasn't the first time a vampire impregnated a human, as shown by the half-human/half-vampire South American native that appears at the end. However, the Cullens knew nothing about his existence until that time, nor could they assume the fetus was fully vampire. They therefore had no idea how to treat Bella's pregnancy.
raywest ★