Well, a lot of pregnant girls would make the rest of the story pretty difficult, but maybe there's a way around that. I mean the world keeps getting reset, with changes each time, so maybe there's an opportunity to fit it in that way. I don't see it as likely either though
There might be a way around that, but there is no way around the resets pushing time back to before the pregnancy and there's no telling if enough time will pass for it to show before the end of the game or a reset pushes time back to before it was showing. Even if they get pregnant, if time gets reset back to before they were impregnated or before they were showing, it might as well not be there.
Even then, if the time frame of the game is too short, it won't have time to develop to the point of showing in that case, either. Remember that there is no magic in this game world except maybe a supernatural force irresistibly compelling player Sensei to act at certain points, the Yumi kiss is a perfect example of this, so there is no way to speed up pregnancy, especially without harming the mother in the process. This makes pregnancy impossible to do from a story perspective unless there is enough time going by in the game for a pregnancy to develop naturally, which is roughly nine months.
I see no indication this game will span nine months of events even with the development taking multiple years by design.
There's also the elephant in the room, player Sensei is trying, and apparently failing, to keep his multiple sexual relationships a secret. Not every girl is aware he is seeing others or how many he is seeing at this point, but some do know he is seeing at least one other girl and several know that other girls feel that way toward him. Ayane and Ami are particularly dangerous in that regard and Sana, being the quiet girl, is also one to watch out for. Kirin is openly manipulative and has evidence that could end at least one relationship, his relationship with Ayane, instantly, so even if she truly has no real intention to cause trouble with that evidence like she says, we can't rule out her acting out of emotion and exposing them without meaning to.
Any of the girls becoming pregnant with really only one guy around that could pull that off because of the war is an instant red flag and player Sensei would be an instant prime suspect because he is so close to them.
