So you really have to progress the Entking fight and MCs event in order to unlock pregnancy for Yona.
I tried for half an hour, with the preg potion, all possible males: No pregnancy.
Killed the Entking, trigger the Yona/Man event, went for the love arc (3 sex scenes) instant pregnant.
So seems like you have to trigger the event to unlock Yona pregnancy.
But once you do and you have a daughter that's grown up, she'll fuck any male that has a Yona animation, so if left unchecked, that girl easily becomes the most laid girl in you camp.
To bad Yona loses her belly in sex animations. (Also still no lesbian stuff for Yona besides Nami. Now I want mother/daughter, so Yona with Yona model, lesbian sex)
Also unfortunately that you still cannot let the other MC fuck around the camp while you do other stuff.
The Children do it why can't the parents.
Also just a thought: If the MCs children go to any character they have an animation for to fuck them, should be an incest village with only MC children explode down the line?