First of all, my condolences. I hope you get through this difficult time, and please realize it is not shameful or your fault. It is very common - this article estimates 1 in 4 women go through it.
Sharing any personal information or change, especially a negative one (miscarriage, divorce, death in the family, etc.), is always difficult. It should be a little easier in the workplace than in your personal life, however, as there is some structure there.
Decide how you want it dealt with. Are you feeling OK with people coming up to you and asking you about it? If so, then you'd just reply to them when they do. (Word will then spread after you've told a couple people.) Since you're asking the question, I assume you don't feel prepared for that. Do consider taking off some time if you can, even though you're "physically OK" to work I don't know any manager in my field that wouldn't insist you take a week off just for you. You might be more prepared to handle the question afterward.
There's no real good way of stonewalling on an issue like this, either. There's no effective way for people to not find out, and you have to realize people will talk to each other about it.
What I would do if I didn't want to have the discussion with random folks is to share the situation with your boss and ask him or her to convey to the rest of the team how you'd like it handled. For example, if you don't want anyone talking to you about it, they could convey a message like "As many of you know, Carol was expecting a child this July. Unfortunately, she has had a miscarriage (or however you feel comfortable describing this - e.g. "She has had complications, and is no longer expecting"). She is doing well and will be returning to work shortly. Please respect her privacy during this difficult time; she'd prefer for people to not discuss this with her at work."
You can also go the gossip route, by asking a friendly coworker you trust that is generally tuned in to to the gossip mill to spread the message and to stress that you don't want to talk about it. Some people, oddly, prefer this route, while others don't like the thought of "people talking about them."
When I was divorced, I used that first technique - just telling people as it came up, and word then spreads quickly enough that most folks stopped running across it. But I have a pretty thick skin, and that was the right approach for me.