I grew up reading about Anne McCaffrey-style dragons. Their biology developed on a different planet, around a different star, and then was bioengineered to become what they were.
My dragons, at least in theory, are Earth-born creatures. Their biology needs to have some parallel to animals we know. For some reason, the soft-shelled eggs of turtles struck me as apropos.
And, recently, I read about what amounts to the egg sickness as described in my story, and had another one of those serendipitous shivers about having extrapolated correctly.
So as to avoid spoilers, I won’t go into any additional details, but recommend instead that you read book two of the Red Slaves trilogy to find out why I had to create a framework for dragon biology.