Elderling Creations Theory (Spoilers through all the books and Dragon Haven)

['thul]

Spoiler

These beings agree the child would probably be changed no matter what stage its parents is at. They theorize further on possible effects of the change upon reproduction.

Length of gestation will naturally affect childbirth. If a child is still fairly small, it will naturally take its mother less effort to push it out than if it is large.
If you think a bit on how egg-laying creatures develop, you'll realize that much (or most) of the development happens after it has left its mother. Since dragons lay eggs and humans give live birth, Elderlings will most likely be something in between. Obviously a lot of the details here cannot just be looked at through the lens of science, but also have to be filtered with magic. The dragons, humans and elderlings of the Realm of the Elderlings are far more genetic and scientific in nature than is common most fantasy universes. Dragons don't just use magic to fly, but have to develop wings sufficiently to do so.