It doesn't play a very big role tbh in the grand scheme of things.
As I mentioned, it only starts coming up in the endgame where you're given the choice to impregnate each girl. The game takes like 5 hours to play through I'd say
Implications of impregnation through dialogue (off-set period, pregnancy tests etc) and conversations with loose plot relevance. You're given the choice for it happening.
Consequences don't occur ingame and are instead shown in a few post-credits images.