How to announce at work

My DH and I have told family we're expecting after we got our good results and scan partly because it was so good to have their support last time. But due to the fact a very obvious bump has appeared and I keep having to go to mysterious hospital appts I think I'm going to have to bite the bullet and tell people at work because I'm so tired of lying. Also have been feeling sad as we said goodbye to Hope last year and people have noticed me being quiet. What's the best way to do it?

My DH has said people had his last office brought in buns and stuff like you do for your birthday but I don't know because I'm going to have to follow it up with and also im worried because...

Any suggestions? Xx