Calling it a debacle seems far too dramatic. Adding the pregnancy system in without being able to really support it seems an odd decision to me, but if that's the direction the dev wants to go, that's their prerogative. Anyone blithely saying "just add the pregnancy pictures" clearly has no concept or appreciation for how much work that would require, but the amount of effort needed to support the system really highlights why it seems a strange decision to begin with.
Anyway, all that being said, I think adding in the framework to support pregnancy pictures through an additional variable on the filename, or some other method, would be good. Gives people the option to add them to 3rd party packs, or the dev to slowly add them to official sets over time. Do an 0,1 or 0,1,2 for not pregnant and one or two pregnancy levels, and make picture selection based on time passed.
Adding in support seems a good idea, at least.
My 2 cents.