That is a big "Maybe" at this point. There is definitely a place for it to be incorporated into the plot. I have even been thinking about how to do so. I just haven't decided whether or not I want to. If I do include pregnancy/impregnation content, it will be very close to the end of the game, so I wouldn't expect it any time soon, one way or the other.
Personally, my opinion is that if you're going to only include impregnation/pregnancy as a carrot at the very end as part of the non-playable happily-ever-after or epilogue then omit it entirely.
The current structure of the story, game mechanics, and premises of the characters is such that either you embrace the risky impregnation sex and fully support it as part of the game mechanics and at least one of the routes or you leave it as a tease that is ultimately frustrated by the actual events. If you include the content as part of the epilogue/endings and add the tag to your game then the people attracted to that content will likely be frustrated or disappointed when they find out that the totality of the content is all of one or two scenes at the far end of hours or days worth of grinding through the game loop. Some less charitable players will likely make nuisances of themselves either because they don't want such content in their fantasies or because what is included is too flimsy and non-committal.
From a game development and game design perspective, fully supporting pregnancy routes and fully supporting non-pregnancy routes for all the variations present is a huge time, energy, and resource commitment on the development team's part. It means combinatorial explosions for scope and likely would involve developing or adapting pregnancy mechanics; whatever the pregnancy mechanics might be would be somewhat at odds with the day-by-day, action-by-action mechanics; at current, nine months of game time ends up being many hours of real time. At the very least, you'll need to consider the scope of in game time that you intend to cover with the non-pregnancy routes given the planned characters and events as pregnancy mechanics would only be really supportable for a scope that involves a year or more of simulated time and events.
If you decided to include pregnancy mechanics up to or beyond birth then there are a number of content presentation issues that would need careful consideration and a number of pitfalls concerning sexual/pornographic content involving minor/infant characters. The writing and legal considerations for that can be quite complex and involved.
If you did decide to go for full support of post-partum pregnancy mechanics and narratives then you could support the classic "the baby is born and is clearly from a different biological father" route; the flimsy way would be to make that an end of the game play, but the more robust way would be to develop the story and mechanics that follow as that would more richly represent and simulate the scenario as well as add significant weight to choices and player consequences; it would be drastically more interesting to have to deal with the cuckolding route where the wife make explicit that she is not getting pregnant with the husband's sperm and she is getting pregnant with here extramarital partner's sperm, and it would be drastically more interesting for the player to be able to play with either accepting the resulting child or children as their own vs rejecting that support and family arrangement; this would all be quite complicated to code as game mechanics for a simulation of reactive characters and would represent a game design effort comparable to a standalone game.
This is all the more true if it is supported for open marriage routes or swinging routes where both the husband and the wife could potentially be dealing with such problems of pregnancy/contraception/family-planning and child support for a number of male and female extramarital partners of potentially unbounded size.