Maybe, but it was said that it was 60 days till birth. So that was either wrong or the values in-game aren't right.Well, given that one month in game equals one season, I'd say three months sounds about right in scale.
As for biology: true, but many games make it way faster (after 2 weeks she knows, two more weeks it shows, last two weeks and a child gets born, or similar). It is a problem between having it realistic and having a playable game with results. I personally wouldn't want to skip through 270 or so days to finish a pregnancy if there was nothing to do (except for maybe the occasional fornication with other girls) in the meantime.
And even then, I would personally suggest maybe making it one month. This is still a game so you don't have to completely stay realistic (not that it does in certain aspects).
And again, what's the name of the skill that lets you see the fertility of the girls?