Surprised nobody mentioned
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yet, not only it does have a decent pregnancy mechanic, but its also one of the best cohabitation games I've played in a while, there is a good amount of content to interact and the dev is still adding more stuff to the game. The game he released previously is also worth playing, as it also has a lot of content and features a pregnancy mechanic (although it's not as detailed as in his more recent game + its loli)
the only issue is that there isn't an official translation for any of the games.