I don't think it's sloppy writing. We just didn't need to know about it in season 1. Season 1 was about Lee and Clem, revealing that she's pregnant may have changed the way of playing the game for some people. Focussing on both Clem and Christa, instead of being focused on Clem.
I'm pretty sure they're keeping it for season 2, since I'm sure we'll see Omid and Christa again.