Not at the moment. But maybe in the final version.
Elementary: the basis of this game is the plot. And 18+ is an addition.
Therefore, the main character’s pregnancy will look stupid and inappropriate. Try asking a pregnant girl if she wants to go into the forest to fight monsters.
Therefore, when the game's story is completed, there is some possibility that additional mechanics will be added to the game. But it’s too early to talk about this yet.
I was more asking why you decided that it'd work for the ending at all, but that makes sense! And a fertilization animation without showing the pregnancy till the end wouldn't work when the player can take their sweet, sweet time actually beating the game.
I'd ask if having a pregnancy debuff before spawning an ally after some time would be a good idea... except the game's not balanced around that and it'd be a lot of work to appease a niche section of your fanbase.
Still, really hyped that you decided to consider it for the ending!