I can see the concern, but I don't think it will be something you have to worry about; for one, like seduce me 2, you have a common plot already, so you can avoid the baby and marriage thing altogether and just imply it at the end like that game did.
For second, I don't think continuations to the story are that maligned; fandisks to popular games were a huge deal in Japan a couple of years ago, though only Code Realize and its fandisks made its way west. From what I've seen, the first one was well received. And even a few indie games have done it; always remember me had one in never forget me that dealt with all the gritty parts of marriage and I for one enjoyed it much more than the first game.
Overall, if you have the inspiration to do it, I feel it's a worthwhile experiment. If nothing, you'll be able to gauge how the market reacts and be better prepared if you ever have another game you want to make a sequel to. Or if you ever want to make a game with a different story structure that has the character marry midway or at the start of the game; another concept that I seldom see in VNs.