Okay would be nice to be parents in the end of the story
Yeah, that's part of it. But there's also the time frame CH plays in, which is just over a week so far. There are of course ways around that, like time skips or having the ending(s) play in a more distant future, but yeah.
The one big reason why I won't add any pregnancy to CH, though, is that I simply dislike it myself. Pregnancy content is very low on the list of things I enjoy and I would hate to have to create scenes like that, which would inevitably lead to them being of lower quality than other scenes with content I do enjoy. :)