Unfortunately, it doesn't really look like a surprise, since the effect of "cum inflation" stops working as soon as the player character gets pregnant.wild, it's a surprise pregnancy, you won't know that you are pregnant
I think it is a bug (or a sloppy programming) which is not fixed by the lazy developer.
In the early versions, cum inflation was compatible with pregnancy, but the latter was not "dynamic".
So, the game in its current state is able to dynamically display either cum inflation or the slowly growing belly during pregnancy, but not both at the same time.
Is it really so difficult for the dev to make these two functions additive?