Hermione was horrified for a number of reasons - all of which would cumulatively exceed the average parchment length. The trap she set for the Incendiaries, that wasn’t really a trap, but could end up that way if things went awry. There was so much uncertainty with that topic alone. And now - a child. A fetus. A fertilized egg at most. Completely new. And Draco was up-ended about it.