Pregnancy events are not added in game yet. They are upcoming feature.
As per what I heard pregnancy event happens to be part of story plot.
So yeah, as long as dev takes to progress till that part of the story, it wont be happening. Just like you, I have no clue about when it would be. But since I care really about the story plot. I dont want dev to rush and mess the beauty of the story for that.
Zim can probably give more explanation if he wants to, but this is what we know so far: https://cor.fandom.com/wiki/Unreleased_Features