Friendly Advice: Don't tell immediately
First, I want everyone to know that this is simply my opinion based on my experiences and, in no way, shape or form, am I trying to tell you what to do.
Wait to break the news that you are expecting and I don't mean wait a month. Wait the first trimester. If you haven't heard, the first trimester is the most delicate stage. Anything goes. Anything can happen.
I found out I was pregnant early. Like really early. I'm talking I basically knew the night of conception. It being my first pregnancy I was bursting to tell it. I told family and friends who took it from there.
At 8 weeks I go in for first ultrasound. No heartbeat, no development. Had some tests, another ultrasound, all to come back and say it's an early term miscarriage. This happened not even a month after I called the family. Talk about irony, I had at least three different congratulations (from friends of family/strangers) the day we found out we had lost the baby. I hadn't heard a peep from anyone outside of the family I had told before then. Go figure.
What I'm saying is to wait. Even though you are excited and happy and want to spread the news and are sure nothing like that will happen to you.....wait. I thought the same thing and I have to say it made the whole experience 1000x harder having to deal with the well meaning "I'm sorry's" and the pity in the eyes. By no means am I saying to never tell that you had a miscarriage. I am saying that while I experienced mine, I found it hard to deal with the public. In hindsight, I would have much preferred to break the news after the fact.
Good luck to all. I hope you never have to go through what I did.