Greetings! Do you know yet if the pregnancy variable that is going to be checked in the future will be able to check from previous game versions, or will it be likely that a new save is needed?
Regarding pregnancy (and any other choices made, aspects, and whatnot) and the save system... I'm making the game so that you don't need new saves in any future update. Old saves should work from anywhere.
You may only need a new save if I make a serious mistake somewhere and there's no way to fix it post facto. Then, and only then, might a new game be needed. And rest assured, if something like that happens, I will report it separately in such a way that it will be hard not to notice (e.g. with a big CAPS caption on the game launch or something like that).
So, don't worry about it. Although it should be noted, I've seen people worrying about their saves more than once lately, for no particular reason. Maybe it's not even related to my work, but to other devs who manage to break their games with literally every update and find nothing better to do than ask players to start over every damn time.