Yeah but that's stupid. You can't lock the whole quest behind the idea that none of the several relevant characters are going to get RNG pregnant.Which was mentioned as a possibility by the developer. The issue they also mentioned was that there's an argument that the dance girls already sleeping around not getting pregnant if the player doesn't go through the dance events right away, when odds are they should do to the lack of birth control and such.
Just give them a hidden status effect where they are 'lucky' and won't get knocked up until the quest is over.
Problem solved.