InSim shouldn't cause a problem with pregnancies, even if you have it in Seasons (you do know it hasn't been updated for Seasons yet, right?).
InTeen does not work with Seasons. No previous version. On the InTeen site, Jase makes that quite clear and suggests either waiting on installing Seasons or removing InTeen and install. If you've removed InTeen and installed Seasons, then played a pregnant teen, you've lost the pregnancy. You can use InSim to age the teen sim then age back to teen to restore the meshes, but you won't get the pregnancy controller for a teen without InTeen.
InTeen is currently in a private Beta, so there's hope for your other pregnant teens as long as you don't play them
