my sim isn't pregnant any more

Remove buffs cheat? Don't use it.

Also, make sure none of mods you're using (if you're using) messes with buffs.

I dont use cheats and what are buff cheats 

 not useing mods and n ot cheating but what are buffs

:cathappy::catindifferent::catsad::catmad::robotwink:

sims.remove_all_buffs, something like that, removes buffs obviously, and visually it cancels all positive and negative moodlets, including "pregnant".

http://forums.thesims.com/en_US/discussion/comment/12837208#Comment_12837208

And that is not a bug really. It's just the cheat's sideeffect.

Check your mods and their description on the site you've downloaded them from.

Some mods do affect buffs and can happen they remove them (in this case, pregnancy buff).

I use the term buffs because buffs trigger moodlets. In this case the moodlet from pregnancy buff will be those trimester 1, 2 and 3 happyness. Another example is buff your sim can have  from self-assured trait. That buff randomly triggers confidence moodlet.

i didnt have buffs anyway so what should I do:robotindifferent:

Weill if you din0t use cheats and don't have any mods, then open Origin, my games, rightclick on Sims 4 and use "repair game" option.

As pregnancy can't just vanish without a cause. If it's some corrupted gamefile data, now you'll repair the game.

where is the repair game button:robothappy: