It may or may not be hard for her to be around you - she's pretty much surrounded by women who have had successful and smooth pregnancies. She has other friends, she goes out to the store, she goes to the gym or to church or whatever - and everywhere there are pregnant women and women with kids.
She may also be aware that lots of women have had miscarriages and she didn't know it at the time - it's something a lot of women keep quiet about. So you don't have to take on the blame of making her feel badly. She already feels badly.
I think if you say you are so sorry to have heard about her miscarriage and ask her how she is doing, that will go a long way. She may be fine, she may not be and want to tell you about it, she may just be handling her sadness privately. It may hit her again when she approaches what would have been her due date. There's just no way to tell. Since it was a very early miscarriage, she probably has few, if any, physical problems so she probably doesn't need any help with anything like meals and so on - that's helpful when someone is further along and has a more difficult physical recovery.
If you're uncomfortable saying anything, you could send a nice "thinking of you" card or something small like chocolates that she might like.
I would be careful NOT to say things like "Don't worry, it wasn't meant to be" or "There was probably something wrong with it" or "It's God's way." Regardless of what one of us may believe, it may not be what the next one believes. This can wind up hurting her feelings more than helping, so I would steer away from any of those platitudes.
I think if you keep it simple and take the lead from her, it will be much appreciated.