My ex and I have been getting along quite well for for the past year. We live in different cities, but we speak weekly. Yesterday he drops this bomb on me that his girl is 8 1/2 months pregnant, and I'm wondering why he would neglect to mention that?
Talk about awkward. Clearly he didn't just "neglect" to mention that he consciously didn't. As for why, it could be a multitude of reasons. Who could have thought you'd be jealous, he could still have feelings for you and didn't want to ruin the vibe (which would happen eventually when the news broke), or it could have just not come up in conversation. At the end of the day it really isn't your business and he doesn't have to tell you anything, honestly.
What makes it weird is the fact that you guys have been in regular contact. It's not like you were the standard ex that you don't talk to for months on end, so my feeling is he either had/has feelings still or just didn't want to have that awkward conversation. I had similar struggles when I got engaged, if I happened to talk to an ex on IM or something do I just say oh yeah I'm getting married. Yeah, I could have but if you're the one that broke up and think the ex might be sensitive you may want to avoid the subject or just decide your ex isn't part of your life like that and doesn't need to know every major change as they happen.
The real question is how do you feel about this news? Does it make you feel jealous or hurt? If so you have to analyze those emotions and deal with them to see where this friendship goes and if it really is a true friendship. End of the day the baby is coming (might even be here by now) and you're just going to have to deal with that. You can congratulate and keep it moving or you can hate because you still have feelings deep down.