Got premade sim pregnant. What happens?

[Cassie]

Well, I think if you choose to enable it, you can have teens WooHoo/Get pregnant with AwesomeMod, I'm pretty sure that's what I did [although at that point I was on a wild CC & Mod spree so I don't remember clearly, haha], but there's a specific hack created at MTS, but I remember it not showing up in my game IIRC, but every game's different so you may as well try as it seems to work for most others. Good luck.

http://www.modthesims.info/download.php?t=348890

I try not to have teens get pregnant much [only done it twice in TS3], but I like to use it occasionally for my more dramatic storylines,. ;P
I get them married a lot though. Dunno why. I nearly always have a spouse set up for a Sim as soon as it's born, so I know who it's going to make friends with as a child and fall in love with as a teen, so I guess that's why.