Does body mesh shape determine pregnancy "size" later?

I noticed that some sims seem to get very large pregnant bellies and other sims do not, at first I thought this was just completely random but I'm wondering now, does this is actually have to do with the body shape mesh you first pick in CAS.

Specifically I'm referring to when you pick from 6 basic body shapes, because that is technically a pre-set body mesh the determines the overall shape of your sim...so I guess it would make sense that the pregnancy mesh would be different too too? Would that explain why some sims get giant bellies and others do not?

Or is it truly just random who gets bigger pregnancy bellies?

Anybody noticed?