Telling your coworkers your pregnant?

I'm starting to consider how to spill the news to my coworkers. My bosses already know, and I'm waiting until week 13 to tell the others. I work in a mid-sized department of about 30 people, and we are split into three sections. I worked with one section for 3 years and then moved to my current section two years ago - so I have strong relationships in both places. I was thinking of making some cupcakes and sending an email to my CURRENT section saying "baby wanted cupcakes, help yourselves" type of deal. But then I would feel bad not including my old section. BUT if I include my old section then there's just the one section left and I'd feel bad excluding them - but if I email the whole department it feels like I'm sending an email blast and making too big a deal. I don't want to look like I'm seeking attention, and I don't want anyone who just doesn't know me that well - or doesn't care - to be put in an awkward position. Anyone have any thoughts/suggestions?